Simply amazing. I must have for any PS2 owner.
The gameplay itself is very fun, and easy to learn. Unlike most RPG's, KH2 lets you just press a button to attack. Then, you can just beat on your enemies till they die. Its actually a very good system, and makes battles frantic and fun. You can scroll through a bar on the bottom left of your screen to access other commands, such as spells and items.
This time around, though there is a very serious problem with the battle system that was not present in the original KH. And that problem is the triangle button. Sometimes, an icon appears that will let you execute at amazingly powerful attack by pressing the triangle button. It is helpful, but it makes the game far to easy. Most boss battles are bassically just hitting the boss until you can press triangle, at which point you will unleash your super attack. You basically repeat this until your done. It makes the game really easy, and I actually only died about 5 times in the whole 30 or so hours it took to complete the game. I've died more times then that in the first temple of The Legend of Zelda: Twilight Princess. The game is too easy, and thats its major issue.
For instance, in KH, it could take days to beat a level (well, not days of actual playing time, but you get what I mean). This time, it takes an hour to beat some levels. And thats including the ridicoulous amount of cut scenes in the game. Fortunately, as I said before, the story in great, so the cut scenes are welcome.
Overall, though the game is too easy, it is still insanely fun and addictive, and has an absolutely amazing storyline. This game is nothing short of a masterpiece, and its a must own for anyone, even if you do not like RPG's.