It was advertised a lot more than the first Kingdom Hearts, and as a result has gotten more attention, both good and bad.
Using characters and worlds from Disney, as well as completely original ones, and Final Fantasy character cameos, they've managed to create a pretty freaking awesome game.
A lot more linear than Final Fantasies, it can't hold up against them storyline-wise, however featuring an incredible Real-Time Battle system it really is a completely different kind of game.
However it is often bashed by so called 'hardcore gamers' for:
a) Having Disney in it at all.
b) Having a 'simple' storyline.
c) Being a 'button masher'.
In opposition to the above:
a) Walt Disney revolutionised fantasy and animation. The movies were all great and the people who make that argument are usually ignorant pre-teens who missed the Disney Era.
b) It is the generic Good vs. Overwhelming Evil, but then, most games are like that.
c) Real Time fighting. Get used to it. It's no more of a 'button masher' than great games like Radiata Stories and Star Ocean.
In conclusion, Square and Disney tried to make a new kind of game and succeeded. Not the best game out there, but very good all the same. If you buy it expecting another Final Fantasy you'll be disappointed, it really is a different type of game.
Oh and it's better than it's predecessor in pretty much every single possible way.
"I can fly-y-y-y (chorus in background) ((as Xemnas opens the Final Door))" -lol, Kingdom Hearts (YouTube)
"((Struggle battles clips with fat guy, Axel and some other guy)) -My name is Thurgood
-Hi, I'm here today because I'm addicted, to marijuana.
-You in here, said marijuana?? Marijuana, man this some bullshit!
-Marijuana is not a drug, I used to suck dick for coke.
-I' seen 'em!
-Now that's an addiction man! You ever suck some dick for marijuana?? ((Axel brandishes his spinny things whatever the hell they are))
-Mmm, no. I can't say I have.
-I didn't think so." -Kingdom Hearts 2 WTF
"((Shakira's 'Hips Don't Lie' plays synchornized with Ursula clips))" -Kingdom Hearts 2 WTF: The Sequel
"(('I Like to Move It' plays synchornized with various Axel and Saïx clips))" -kingdom hearts on crack 12 parody ~The Classics~