Great game, but with some disappointing flaws.
Gameplay - Gameplay is what basically defines a game, and it's KH2's weakest point. First of all, this game is far too easy. For me, Hard mode just barely passes for a Normal difficulty. Barely. Normal is pretty easy, and Easy...you can't lose. In the last game, magic was extremely useful. It could decide life or death constantly in KH. In KH2, though, the only magic you need is the Cure magic, and SquareEnix screws that up by making cost all your MP. Sure MP heals, but it's really stupid when a Cure spell costs all your MP. All you need is the X button, really. That itself will get you through the whole game. You can press Triangle to activate the Reaction Commands throughout the various battles, but they're just for show. There's pretty much no exploration, conversations pretty much get you everywhere. That's the next flaw. In KH, there was lots of exploration, and you could even get lost a little. In this game, there is no possible way to get lost. Seriously, you can't get lost in this game. Graphics - The graphics in this game are absolutely splendid. Everything is clear and all the moves and stuff look great.
Sound - The music score in this game is the other strong point. It's really good, especially the battle themes.
Story - The story's pretty decent. Sora got way more naive in this game than the last, he somewhat ruined the story himself. The other part that ruins the story is the fact that it takes up 2/3 of the game. You spend less time fighting than listening to people drone on and on. The convos are interesting, though...
However! In these various Disney worlds, Sora and friends go through each world based on their representing movies. (e.g. Mulan needs to take down Shan Yu, getting the Black Pearl back from Barbossa, etc.). In other words, during the first visits to each world, they have pretty much nothing to do with KH2's story. Not until you revisit each world does the story continue to roll in full force.
Well, that's basically all I have to say. SquareEnix thought it would be better to lower the gameplay value of this game to revamp other qualities, and it worked. If the game was a bit more challenging, was geared more towards RPG style like KH, and if there was a lot more exploration, this game would have received at least an 8...