Hopefully we won't have to worry about it being a disappointment. Epic Mickey is quite a different game than Toy Story Mania is. (Which in my opinion, was made for no other reason that to capitalize on the success of the ride). Epic Mickey on the other hand is being designed by Warren Spector - a true legendary game designer, think Dues Ex etc. if your a gamer.
I'm hoping it lives up the hype, as it looks fantastic.
I'm also undecided as to which platform to buy it on. Last word is it may be made available on the PS3 and Xbox 360 as well. Considering the beauty of this game, graphically, I think the HD capabilities of the PS3 or 360, would make me buy it on either of those over the Wii. (Considering I own all 3 systems, I like having options, LOL).