Kingdom Hearts II does a great job in resolving the story at hand, but the journey there is far less rewarding....
For veterans, I strongly recommend choosing the Proud Mode difficulty setting, as anything less is only going to undermine your ability to play video games. The careful coordination of the original is replaced with timed executions of Triangle interlaced with repeatedly pressing X. What's more depressing are what the worlds have become this time around.
Places that were sprawing epicenters are now reduced to 4-5 screens of confinement. Even Atlantica, home to one of the more badass KH bosses, Disney's own evil undersea queen Ursala, has been replaced with a timid and watered down (no pun intended) version of DDR. Of course the game is kind enough to make the reward for its full completion one of the rare ingrediants for the Ultima Weapon, meaning even die-hard denizens who refuse to go "under the sea" will be forced to at some point or another.
Not that Ultima is remotely needed to complete the game, rather its only purpose seems to be in slaying the equally toned down "Son of Jenova" (to which if you wish to relive this enjoyable, yet easy brawl, you'll need a second save file. No rematches for Sora this time). The main storyline can be completed in roughly 25 hours on Standard, which by that time our boy wonder Sora will have become a demi-god of Keyblades. Between ungodly Limit Breaks and Transformation Drives, the game is almost willing to let you complete it. The problem is the only true motivation to do so is to find closure with Sora, something the Disney world's direly lack.
Through some fancy loophole with Organization XIII's meddling, Sora needs to re-open the gates to the worlds of Disney. And while places like Port Royal and Space Paranoids (Tron) are interesting ventures, other places find continuity issues with the original. People remember Sora, but it's like deja vu all over again. Each world needs two visits: one to relive the motion picture and another to stop the Organization from making mischief. After 10 hours, it becomes tiresome and predictable. "Hi Aladdin, yeah it's been awhile. Jafar again? Didn't we stop him? *sigh* Fine. *Jafar dies* Yay, it's over. *time passes* Hi Jack, yeah it's been awhile. Oogie Boogie again? Didn't we stop him? *sigh* Fine." The game tries its best to prevent overall boredom by adding in snippets of storyline here and there, but it isn't until the ominous final world where it all becomes interesting and worthwhile.
The game visually looks remarkable, and boasts one of the greatest soundtracks to come out of Square-Enix. But the core game itself is a hollow shell compared to its predecessor, regardless of the issues that were fixed (free-control camera system, Gummy Ship battles that were worth playing, etc). I'd recommend it for people looking to resolve the storyline, because as much as it'd be a credit to just save you the $50 and tell you the ending myself it's worth seeing. But as one who's been looking forward to this game for so long, I had to look past the "ZOMG! SORA IS UBER!" aspect and see the game for what it really is. It really pains me to rate it so low, and I was hoping it wouldn't be this way. But for me, it really wasn't worth the adventure.
In the end, Kingdom Hearts II relies more on flashy gimmicks and tricks than what the game tries to preach: having heart.