I'm actually impressed with FFII's battle system. It's almost like how they're doing with skyrim...No class system but it's determined by how much you're using particular skills. If you use a fire spell it's going to get stronger to be fire 2 and so on.
I actually found the system to be horribly broken. For instance, to level up a character's MP, they have to use a certain amount each battle. During my time with the game it was leveling incredibly slow. I didn't have enough MP to make it through long dungeons and fight a boss. My spells were leveling up faster than MP itself, which in turn raised the MP cost per spell since you you no longer have the option to cast the weaker spell like in every other Final Fantasy. One aspect of MP management is simply not casting a spell, but because the game lacked a Defend option, the only course of action was for a mage to attack physically, raising Strength and lower Intelligence.
I see they added a Defend option in the PSP version, so I may give that a try, but as of now it's one of two games in the series that I hate, based solely on the leveling system. The story and characters were great though.
I'm watching HCBailly's HD let's play of FFXIII (on YouTube), and really enjoying the visuals, character/enemy design, and battle mechanics.
Is much known about XIII-2 yet, or is it pretty much just the trailer?
A few tidbits here and there. The game will be more fantasy oriented, compared to XIII's futuristic setting. The development team is attempting to flesh out the world and make it seem more alive, presumably by adding NPCs and such. There have been talks of towns, shops, etc. making a comeback, but no confirmation yet. The battle system will be an evolved version of XIII's.