Just, everything! The music, the story, the battle system, the environment!

There's only one thing I was dissatisfied with, and that's this part of the ending:
(SPOILER)
Nobody should have woken up from crystal stasis fine and dandy. Fang and Vanille didn't wake up until centuries after they were crystallized, and only because they still had a focus to complete. If it were a case of "oh well all the fal'Cie are dead so they're free!" then Fang and Vanille should be free as well. It just doesn't work!