I did the MInnie last year and am undecided for this year.
It was really fun, and the distance (9-ish miles) is nice. The Minnie medal is adorable and the race shirts are not unisex, which is a nice touch. Rumor has it that this is the last year for the MInnie and that it will be replaced with a different race next year - possibly a princess-themed 1/2 marathon.
The unique part is that it is a women-mostly race. I would say women-only but some men do run it. The only reason I'm on the fence about signing up is just that it may not fit into my training schedule this year. The course was a lot like the last 9 miles of the full marathon. It started at the Animal Kingdom parking lot, headed toward WWoS, had a hairpin turn-around, then through the Studios, the Boardwalk, and finally Epcot. It would be a good warm-up for women looking to do a 1/2 marathon in the summer months or a full in the fall.
Minnie Marathon 15K - 4 May, 2008
Tower of Terror 13K - 25 October, 2008
Goofy's Race and a Half Challenge Plus 5K - 9-11 January, 2009
Princess 1/5 Marathon and 5K - 7-8 March, 2009