I've had the chance of having a crack and the Wii Fit @ Nintendo Head office as I work for Kmart, its a fantastic little unit that will appeal to everyone. You can even do other excercises using your legs like ski jumping, header a soccer ball and use the wii remote (not the board) to run on the spot and chase someone.
With mario kart wii confirmed for april release this will be two fantastic games coming out so close together.