-Persona 3&4-
Main Character dies = Game Over in any game where you can have three teammates with revival magic, plus hold onto 99 or two different revival items is a completely idiotic mechanic. Considering that the game is well known for being pretty tough, and having regular enemies capable of completely turning a battle around on you at the drop of a hat, there is no reason for it to be there. The game is already tough, this does not add challenge, it just adds frustration.
Sorta fixed it in 4 with your teammates being able to take single target attacks for you, but then the game forgot that 90% of the enemies in the last third of the game use nothing but AoEs.
Also, #4, the teammates you gave me are totally awesome and I love them, but you did not do character development nearly as well as #3 did. Almost 100% of a character's development beyond obtaining their Persona takes place via optional Social Links (The only exception being Teddie).
This sorta diminishes the impact of a character realizing and fully accepting themselves and what drives them (Rank 10 Social Link), when you realize it has no impact of the story. Unlike 3 where the character's realizations were caused by events of the game, and played out to be an incredibly important part in attempting to fight against an utterly hopeless situation.
-Phantom Brave-
As expected by NIS, your ability to design a character's stats to your liking is absolutely wonderful, even more so considering that every single stat can be used as your damaging stat, and every single weapon can learn virtually any ability and be tailor made to be your ultimate weapon.
Your Speed stat is broken to a stupid degree though.
If a character doesn't have high speed, they are dead weight. Your enemies will either get so many more turns than them that they will always die regardless of how much defense and/or resistance they have. Your faster allies will always kill enemies before them and net exp more exp. You can't even just make a slow, defensive character to block enemies in because of how moving around the battle field works.
They will gain levels slower, and because of how stat growth works, even if they do remain even with everyone else the gap of speed will do nothing but widen and solidify their state as a useless lump.
This also makes maps with high amounts of rock items to confine to incredibly frustrating and equipping non-fused axe weapons to completely screw you over unless the character has Quick Attack and you just want to use them for one initial strike.