Leaving aside the fact that this game's intro is an atom bomb of emotion and nostalgia, leaving aside how much of an imprint the story and art have left on me... yeah, it's still effectively perfect.
I normally hate it when people describe a game's style as "cinematic" since, you know, video games shouldn't aspire to be more like a noninteractive medium. But KH2 is definitely cinematic... in a good way. Every aspect of the gameplay, from the Gummi Ship to motion to Keyblade combat, is over-the-top flashy but doesn't deprive the player over control for the sake of spectacle... well, barring some Reaction Commands, but those are far more bearable than the sort of QTEs that God of War popularized. While you can certainly get away with button mashing to some degree, it's on the high difficulty settings that the gameplay really shines. Sora's moveset gives you a ton of defensive options to bail yourself out of the many, many one-hit kills that Critical Mode dishes out, and an equally impressive arsenal to punish any opening you find. Dodge, punish, stagger - it's what all action-RPGs boil down to, but KH2's execution of that rhythm is incredibly satisfying and rewards skillful and precise input to a degree you wouldn't expect from such a casual/childish-looking game.
Of course, good gameplay doesn't matter without good level and enemy design. Thankfully, KH2 is also an incredible game in that regard. The levels mostly eschew the misguided platforming elements of KH1, without being flat and featureless. The real treat is the bosses, though - there's an absolute ton of boss fights, even more of which are added in Final Mix, and almost all of them are exciting and challenging. A few, like the Hydra, are a bit too scripted and unintuitive, but for the most part the gimmicks actually add to the fights rather than detracting from them. The super-extended final boss sequence is a testament to the seemingly limitless creativity and design skill of the dev team, and despite how it never seems to end it's the sort of final boss you play through again and again just
because. (The badass boss theme helps, of course:
https://www.youtube.com/watch?v=8ygh4k2AyBw)
I don't even know what to say about the plot. It's pretty evident that Tetsuya Nomura is out of his mind and is just making up plot elements as he goes along - this is even more obvious in later installments like DDD - but the plot is so loony and takes itself so hyper-seriously that, rather than being the glorified fanfiction cringe-magnet you'd expect from the series' fanbase, it's entertaining to watch the cutscenes just for the sheer fun of taking the piss out of them. If you want to do a drinking game and take a shot every time someone says "darkness", be my guest, but you'll probably die before the end of the prologue.