I think Rebirth did a good job with improving player side gameplay. Majority of the additions ended up working pretty well for the core combat mechanics. I think Rebirth isn't as tight of an experience as Remake overall due to the new additions, but I ended up preferring the greater flexibility and variety at a loss of quality of encounter design.
I think synergy skills mostly had a positive impact on combat flow. Most of them are fairly useful, even if some needed to be used in an unintentional way to be effective. I thought synergy skills would end up lacking due to lack of interaction with other mechanics, but what you get being based on the party composition ended up being sufficient for me. Synergy abilities are also fairly effective and the stun lock component is generally useful, but there is a bit more variance in effectiveness. Limit break plus is the generally good one as it raises LB level and does good damage. Stagger plus is good damage but completely useless for purpose of stagger extension as it locks two characters from doing damage during it. I think it would be better if stagger plus paused the timer from activation to end of recovery, and the animation length can be adjusted accordingly. Infinite MP is pretty good early on but falls off once mp absorption comes into play. It might still be occasionally useful in hard mode but its low damage (with a few exceptions) will make it lackluster I think. United Refocus is mostly only good on several characters as they need to have the ability to quickly build atb as well as quickly cash them out at a moments notice.
My biggest issue with synergy abilities was still that it's not worth using frequently enough in general encounters. There are several causes, such as much more efficient return per atb usage and weak enemy group composition. The game never added that one elite with about 30k or so HP even towards the end of the game to enemy groups, so kill time for most encounters remained under 1 minute instead of around 1.5-2 minutes which is what's really needed for synergy abilities to come into play without being overkill. I hope synergy abilities see more frequent usage in part 3 regardless of how it is approached.
Another minor concern I have with synergy abilities is that synergy gain can vary greatly across characters, and there is also notable difference between the main and the subs. This creates a decent surplus of synergy in many party setups that become wasted, which isn't inherently an issue but it really bugs me that resource is being wasted. I think it might help for there to be another way to use synergy.
The defensive additions were mostly quite strong and most enemies are unable to really deal with these new options in vs. 1 situations. Parry is lenient and having an option that neutralizes damage completely really throws the combat flow greatly in player's favor compared to Remake. The added invincibility to dodge is actually really good as it's extremely low iframes so it's situational enough but still allows for certain attack types to be added to improve enemy moveset variety. Weapon ability and synergy skill options are extremely lenient, and even atb cost of weapon abilities doesn't really even it out in many situations due to atb return on success. The addition of unblockables does help a bit and there are attacks that have enough lingering hitbox to go through the long invincibility frames, but overall I think enemy design wasn't able to keep up with playerd side additions. Encounters really need to have multiple elite or strong enemies as that's the only situations where there is enough attacks flying around that the lenient window and powerful effect doesn't feel out of place.
Summon remains the weakest part of the combat system for me. With how efficient each bar of atb is now, the up front cost for summoning is now prohibitively expensive. On top of that, summons don't trigger till first stagger and the ultimate doesn't trigger for a good amount of time after that and with the current average ttk for vast majority of encounters/bosses will never last long enough for summons to matter even if you make an effor to make them work. I think it might be worth having the summoning use synergy instead of atb as a way to get around that, and the current extra conditions for summon usage are outdated and should be removed if summon strength remains as is.
Weapon abilities remain extremely high quality mostly and the ratio of useful abilities, while lower than Remake in my opinion, remains really high as well. This remains extremely impressive to me especially with a larger party in play.
I ended up liking that every single character basically has an install of some kind. I thought everyone having one would make it less unique but they are different enough that it didn't turn out that way. Even things like prime mode which is just a superior replacement to normal punisher came out ok in practice.
As for more character specific stuff,
Cloud- He isn't the best at anything, but has value as the most balanced character overall. He is basically second or third in most stats and also second or third choice for most roles and can be mixed and matched in loadout to fill any hole in the party. He does have an unique function in Rebirth in that he is the only character that can output good damage in stagger phase with no resource requirements thanks to melee blade. This allows for more liberal use of atbs outside of stagger phase and he even allows for net positive atb gain through stagger phase. This will make him extremely valuable in the party even if he is not the best character at any role.
Braver remains a great benchmark for damage abilities. Triple slash is Cloud's best move to generate synergy due to speed. Focused thrust remains benchmark for stagger build-up. Disorder is a great opener for burst opportunities. Prime mode opens up a ton of utility as well as damage potential. Infinitiy's end is useless due to existence of melee blade. Blade burst works fine as a magic version of braver. Counterstance is largely irrelevant due to counterfire being usable in punisher mode. Overall a pretty diverse set of abilities offensively for single target that is a little lacking in the utility department.
Barret- Amazing as a sub character due to overload. While atb generation is reduced greatly for AI controlled characters, switching to barret and using overload then switching out generates normal amount of atb and overload generation isn't reduced for AI so barret's atb gain is extremely healthy as long you check on him now and then. This makes him the best support character in my opinion as he can keep up in atb generation with a materia loaded Yuffie. His damage efficiency per ATB is not good, but his damage efficiency per button press is great, which is really nice for a sub character as he requires very little babysitting. He is great as a third during stagger phase as you can just drive by him with a button press and get mileage, be it overload or an actual weapon ability. His synergy abilities are on the more mediocre side.
I mostly didn't use steelskin so no comment. Focused shot remains the best stagger build-up by a large margin (3 bar is basically instant stagger when hitting an elemental weakness). Maximum Fury is a good AoE-equivalent option for clearing trash. Bonus round is a great install that adds significant stagger build-up. Lifesaver is situationally useful just as before. Charging Uppercut is lackluster due to long animation length and you basically get the same amount of overload charge using the extra time on normal attack instead off other abilities. Point blank is a great ability withs fairly efficient damage, a ton of armor, and cannot be thrown for some reason. Smackdown is decent AoE, a great CC/interrupt, and makes Charging uppercut irrelevant. Lifeblood cannon has a line aoe and micro-stun on the initial hit which gives it a lot of utility. Turbulent spirit is more atb which is great. Barret has an amazing set of abilities with tons of utility in supporting the main in single target instances and being the main in trash clearing situations. He is perfect as the second or third character in a party.
Tifa- Tifa remains the best character for stagger as she is always ready for it in practice. Like Cloud, she doesn't need to go into stagger with additional resources to get good damage which reduces the amount of time needed for her to be ready. Some of the new additions also allows her to play more than just the multiplier battery role, and she can comfortably fit as either main or sub in a party. Her damage outside of stagger is a little lackluster compared to other main/point candidates like Yuffie/Red but she more than makes up for it during stagger. Her offensive synergy abilities are fairly situational, but her defensive one is very solid and helps her play point.
Unbridled Strength remains an amazing basis for her kit. Divekick is braver which is great. Focused strike helps Tifa run point when needed. Reverse gale has an element which makes it decent occasionally but it's magic which isn't good on TIfa. Overpower is good for fitting damage in tight windows mostly. Starshower animation is too long, making it really inefficient. Chi trap is not good due to its stationary nature, and unfettered fury places a free chi trap that's a shorter, more effective duration (I think chi trap should work more like lightning rod with the normal fury string having the ability to move it around instead of just genrating a free one). Unfettered Fury is great as lvl2 attack shores up her stagger build-up nicely. True Strike is a situational replacement for omnistrike, being faster when charge is taken into account but doesn't return atb. Trinity Strike is a really efficient damage per atb ability that's long enough that it can't just fit anywhere so it doesn't replace divekick outright. Tifa doesn't offer much utility but she does her main role really well and unfettered fury allows her to more effectively fast track to stagger so she doesn't need to rely on other party members to carry that load as much.
Aerith- Aerith remains a turret and can still crank out the most amount of damage over a 15-20 second window, but she requires a lot of setup and attention to make things happen. There are definitely more bad match ups for her as her defensive options are just ok, which is problematic given that her attacks all have bad recovery. She is quite a bit more materia dependent as well as having the right ones make a much bigger difference for her than most other characters. She should definitely get first dibs to a lot of stuff when she is in the party, and while she is likely the main dps when she is in the party, she will need someone else to play point frequently
Soul drain remains solid options. Sorcerous Storm's melee range remains a notable downside in boss encounters. Arcane ward is good. Radiant ward is amazing, but it does cut into the function of tempest and familiar pretty harshly. Chrono Aegis is only useful against trash. Lustrous shield is situationally useful and not being omni-directional remains a notable downside. ATB ward is still good. Ray of judgement is too slow and will only be useful as the very last option. Trascendence is a great install. Noble Sacrifice is only relevant in the most situational instances as it costs 2 atb. Aerith has some duds but the good abilities are really good. She can really only be played one way but she is really good at that one way.
Red- I think Red is the best point character in the game once he gets retaliation, which also changes his gauge management completely. Red can crank out more damage outside of stagger than anyone else, but his damage during stagger is also near the bottom. He has defensive options to cover for every situation as well, and ends up having pretty decent utility. Red has really bad match ups against enemies thath ave a lot of unblockables as he can't generate gauge unless hits connect, so ideally another character in the party can play point when those bad matchups show up.
Sidewinder is a great ability to default to. Stardust Ray remains a great crowd control ability throughout the game. Sentinel stance is good early but mostly gets replaced by other defensive options later as it isn't atb efficient. Cresent claw is not good as it's a directional AoE, and Ray just does crowd control/AoE damage better. Chilling roar is subpar as it's magic damage and it's the same gauge generation condition as normal (it would be better if this ability allowed for gauge generation on dodge). Supernal Fervor largel falls out as it costs 2 atb and better 2 atb options show up eventually. Respite is a decent heal and may be more useful during hard mode. Spirit is a great ability and is the full gauge option whereas retaliation is the low gauge option. Retaliation is Red's best ability in my opinion as it gives him a lot more flexibility in how to use his gauge. Reaper's touch is amazing damage per atb use once below 50% HP but it's hard to get Red to 50% naturally. Red also has some duds but the good ones are really good and while it does take a while for him to feel complete he is great once everything is in place.
Yuffie- Yuffie is a great hybrid character and has the most consistent damage output out of all characters. I feel like offensively she is even more well rounded than Cloud, and Cloud's advantage is mostly superior stats which helps in making him play support more effectively. She also has a lot of interesting extra mechanics with a lage part of her kit due to her ability interaction depending on where the Shuriken is. which is quite different from other characters. I think Yuffie really needs to be the main if she is in the party as the drop off between player to AI for her is much larger than other characters due to how art of war works. She is a really strong point just like Red with a good number of strong defensive options.
Art of war being a continuation buff makes Yuffie's playstyle a non-stop offensive type which is fairly unique. Brumal form makes everything work as it makes continuation reasonably easy to achieve. Ninjutsu is just nice flexibility to have. Blindside is amazing as it's a stun breaker/recovery cancel while also working as a dodge with some iframes. Windstorm is a good AoE for trash. Doppelganger is a great install. Shooting star is a decent DoT ability. Banishment is just more damage which is good. Storm's Fury is a great 3 atb cash out and makes refocus really valuable on her. Purification is more of a heal which is just ok. Yuffie has amazing utility, even if it's mostly selfish, and she really has no duds to speak of. Offensively I think she is able to do it all, and even if she isn't the highest damage during any particular situation, with sufficient resources she can get really close. She needs to be the main to shine though, in my opinion.
Cait- Cait is the most lackluster character of the current group in my opinion but it's less that Cait is objectively lackluster but more that the rest of the group is extremely solid. I think he is just slightly off in many areas. Most commonly, a lot of his animations have that extra flair to give him character which is really nice visually, but it also adds like .5-1 second or so of startup or recovery which makes his combat flow feel off compared to other characters. Kaboom and magic can have a much shorter startup in my opinion. I think that they should also lean into the two-character design a bit more and further de-couple cait and moogle's actions as a solution if they want to keep those extra animations and make up time by having Cait be more active when a moogle specific weapon ability (such as fortune telling when riding or moogle knuckle) is used, or the moogle when a Cait' specific ability (such as dice or lady luck) is used. In general, just a notable increase in frequency of action for Cait should be enough as fundamentally his kit is really solid despite its random nature in a lot of places.
Let's ride is ok for its necessity. Dodge n' Dive is a good ability but needing to resummon the moogle afterwards can make things feel al ittle cumbersome as is. Dice is fine. Fortune is good. Kaboom takes a little too long to prime in my opinion. Mine can be a bit too random. Magic is just ok due to its mostly single use nature. Knuckle is great. Lady Luck is solid. Lucky slots is lackluster as it's 2 atb and the effects you get aren't amazing considering how long you will be stuck in practice. Cait mostly moves fairly well when just attacking normally, but currently his abilities has notable negative impact on his combat flow due to excessive startup or recovery at various places. I think he can also benefit with more situational extra mechanics like Yuffie as he fits the hybrid archtype as well.
Overall I think they continue to do a great job with playstyle design of the characters and weapon abilities continue to be mostly great. There is also enough variety between them that party composition has really healthy diversity. I look forward to seeing how they approach Cid and Vincent's design and fit them in.
