A lot of wasted potential. Not a good Final Fantasy game.
1) Make the characters INTERESTING. This is one of the games weakest points. The characters are ridiculously boring. You don't grow attached to any of them because the game just doesn't bother going deeper into the character's stories or personalities, at ALL.
2) Change the battle system for the better. Turn-Based maybe be unoriginal and bland, but I'd sure as hell have FF10's battle system of this "real-time" rubbish. You can move around the characters while in battle, yeah, but it doesn't do any good. At all. You still manage to get hit by the enemies no matter how far away you are, and you can't do anything about dodging or blocking the attacks.
3) Completely scrap the summoning system. The summoning system in this game is absolutely APPALLING. The actual designs of the espers are amazing, but you are MUCH better off not summoning them at all.
4) Make the story accessible. FF12 tries to hard at being deeply political, but it just comes off as confusing.
This game came as an absolutely huge disappointment to me, as I had been anticipating it for at least two years. What with the massive year long delay, you would think Square Enix would have changed a lot of stuff with this game, but apparently not. Fortunately, it's not all bad. The locations are gorgeous, and the main story + sidequests lasts well over 100 hours. Still, I strongly recommend you either skip this game if you're expecting a traditional FF game, or just pick it up in the bargain bins.