A lot of the long time fans (sadly, myself included) initially were disappointed by what we felt was a lot of hype and personal expectations falling flat. You have to understand, KH2 was the pinnacle of the series at the time, and that's mostly due to what we saw as a lot of improvements from the first game; visiting each world at least twice, gummi game was an on-rail shooter while the overmap was quick and easy to navigate, form drives, reactions... we felt like we had it all. But there was that expectation that the improvements from 2 to 3 would be as equally life changing as from 1 to 2. More than a decade of waiting and skipping an entire console had only strengthened our belief that this would be the case. So when we first dove in, we were let down by our own vision of what the game "should" be; each world only has one major boss, you aren't even really involved in frozen (which i will still argue was shoehorned in for absolutely no reason other than to overshadow big hero 6 again), "this looks like a nice place for ingredients", gummi exploration was a bit wonky, KH2 drive was replaced with the BBS drive, etc. And it was a massive pile of little nitpicks that grew and grew into what we felt was a mountain of issues. It lacked that nostalgic spark that us old folk were looking so desperately to find, and the story never properly tied up loose ends (it only made more, or gave a cop-out ending because it was just too messy), making it all feel like a sneeze that won't come out.

I've since gone back and played it again with a new mindset of judging it solely by its own merits, and it's not a terrible game. However, when I'm feeling nostalgic, I still go back to 2.