Probably the pinnacle of the KH series in terms of gameplay - the combat builds on the original and makes Sora feel fluid and powerful, but not yet so broken that you just have 'push this button to win' for the main storyline. Some of the story cracks start to show here - especially the growing divide between the Disney sections and KH plot sections, which in the original fully intermixed, but increasingly are separate (which only got worse in later entries). Here, it's not too bad, since you revisit worlds, constraining the writers' ability to just have you play the Disney movie, and the story is self-contained enough that you can get by. The addition of Drive Forms in particular adds a lot of depth to the combat - even though this lacks the many superbosses added to the Final Mix version.