I'm about 25 hours of gameplay into it and have the following to say.... most of which is spoilers
1. Combat: I like it. It is very easy to pick up, but very very hard to do it fantasticly, like most good games. You can go through hundreds of enemies while only pushing the x button, but you are rewarded when you go more advanced. When you are going nuts with two keyblades, casting spell after spell, doing twin boshidos and shooting stars with Auron... it is gamer bliss like I haven't had before. Also the utilization of the Triangle button during boss battles makes for, if you can time it right, fun side games within the battle. I don't have anything bad I can say about the fight system. If it is too easy for you I suggest discovering all the ways you can to beat your opponents.
2. Menu system. The animated Menus that are specific to each land you go to is a neat extra.
3. Story so far. It is heartbreaking. After finishing the preview I almost cried for poor Roxis. Poor all of them, really. I can't wait to see how it all ties up.
4. Worlds. Just finished the Pirate world... and freakin' loved it. All the worlds provide very interesting situations and enimies. Though they do seem kind of small. I think this isn't a real size issue. I think the issue is there is almost no platforming or puzzle solving to be done, something that has kind of disapointed me a bit.
5. Music. I personally like "Simple and Clean" better than the opening theme for KH2... but I haven't heard anything that I don't like yet.
6. I've died a few times... From what I can tell, if you die in a boss battle then none other than Mr. Mickey Mouse comes into play to res. you. You have to charge up his "light force" first which makes for an interesting and rewarding mini-game that almost makes me want to die more.
7. Graphics. Top notch. Belle in particular looked fantastic to me. The Pirates, including Jack, were passable, but Barbossa was head and shoulders above everything else. Can't wait to see what everyone else looks like. I think the Disneyland Commerical people should take a note from Square and make their 3-D characters more like these.
8. At times during key fights side line characters may shout advice to you. I find it repetitive and annoying. I don't want to hear Cogsworth every time I move repeat "Master, compose yourself!"
9. The subtext to the story is subtle and moving. For example, when Mulan is dressed as Ping she is a passable fighter at best with no special moves. When she is acting like herself she is capable of fantastic moves with killer combo moves with Sora. Little things like this are evident everywhere for those who care to look.
10. The last game that took my imagination like this was grand theft auto San Andreas. In GTA it was the sheer diversity of gameplay that held me onto the hundreds of hours wasted on the PS2. For this it is the story and the discovering that does it.
Of course, I'm only about half way through I reckon. Now excuse me while I kick some heartless butt. And if you see any nobodies point them in my direction.