I will say building the gummi ships is pretty fun. Flying the things between worlds is just kind of boring for the most part, and it can be tedious as well (at least for me). My main problem is that you don't really have access to the cool gummis to build an awesome ship until the end of the game, really. I made an awesome ship at the end of my first play through of Kingdom Hearts, but then I used it once to see it in action and that was it. The flying part just wasn't fun/worth it enough to do after you got the pieces to build an awesome ship. But that's just me. There's nothing wrong with enjoying that part of the game, and really the only reason I put it as a negative is just because most people I know hated the gummi ship segments. I'm mostly indifferent about them myself.