I thought FFXIII was nicely done myself, though I can think of 2 things I would change. 1 is the fact that you are stuck with whatever leader you have in battle. What if I find myself wanting to be Lightning at one point in the battle, then Fang in another, I mean, c'mon, Army of One is a kickass move, and Bahamut is a kickass summon.... maybe they should be on the same character even....
the other thing is the battle theme... I don't like how they get to the action part of the song... I find that I don't find myself humming the battle theme every time I get in a battle, like I did in past games in the series.