So...what's your opinion on the new Wii Fit?

I can see good potential in it, but you need to get out what you put in financially. If you buy one and decided it's just not floating your boat in less than 10 uses, you waste money.

You still could be wasting money ater a point like that, if it's not used enough. Good enough though in my opnion to be considered useable.

what is it?

It's technically a game, but more of a basic training program which uses body weight exercises. Here http://uk.media.wii.ign.com/media/949/949581/imgs_2.html just flick through the images and it should give you a good idea what it's about