I really love the big worlds, and how hard it is to look for the treasures. The treasures really felt like treasures because you really had to search for them. And Riku's Character Development.
Although I'm STILL REALLY CONFUSED about the Realm of Sleep. Did they really time travel or what? My head hurts.
they really did travel back in time in the beginning(though yen sid's magic deaged them), as being on a world at the moment it falls into darkness is otherwise the only way to enter the realm of sleep. Yen Sid immediately afterwards brought them back. What really gets me is they should've kept their bodies in the Tower.