I recently just beat the game (Re:coded) and at first, like the first two worlds, I was a bit disappointed.  Shortly as the story progressed I got more into it.  I wouldn't say this is the worst KH game; they're all very, very well made.  I enjoyed everything about the game.  The story, the battles, the bosses, even the annoying bug level thing.  It is definetly at the bottom of the list for KH games, yet it does not earn the "worst" title.