I like this thread.

FF8: This game was one big example of terrific and ambitious ideas that were all poorly executed. The underlying story is actually quite interesting, the idea of having enemies level with you is something I think needs to be worked on again (though, if they level with you, why have leveling?), it's been proven with games like Dragon Quest VIII that forging weapons can be a lot of fun, and gaining magic from enemies is another good idea that I think could be made into something not boring.

FF10-2: The battle system... That's about it.

FF13: The battle system. Oh, and Fang and Sazh are pretty cool.

Crisis Core: Unlike other Compilation titles, the "game" itself was a lot of fun. Too bad it was ruined by an atrocious villain and Square finding the need to reinvent things that happened in the original game (none for the better).

Dirge of Cerberus: Okay, there really was not a single thing that I liked about this game. Sorry, I tried to think of something, I really did.