My problem with it was it just wasn't solid enough with it's execution, so I just ended up being annoyed with it.And this is a problem... how?
XII's "battle system" was perfect for what it was trying to do: Erase a lot of the tedious busywork of the combat in JRPGs away. Instead of you smashing X (oh, sup FF13) it's the game smashing X with you doing minor course-corrections if things get really hairy.
Still the best combat system.
You could only have a limit amount of gambits, and you couldn't save a "set" so frankly managing them was extremely tedious. You also had to go off and buy the "conditions" which felt a bit daft. Manual input wasn't really a viable option either because the menu's were clunky to navigate through.
Honestly I'd like some kind of hybrid between the two.