VIII. Draw system was Lame, as was Junction System. Your Characters were basicly Clones, except for their Limit Attacks.
Underdeveloped Supporting Cast, Main Character and his Love Object are two of the most annoying Characters in all FF, and basicly everything is focused on those two.

People say X-2's battle system was good, but with how easy that game was it really didnt' matter. I didnt' know if it was a good system or not, and there isn't even a point in using all it has to offer.