There was a blog by one guy who travelled the US in his van and did his Wii fit excersize every day. Can't find it now, but the conclusion from the guy was that he did lose weight, he got fitter, built muscle, etc... etc...

Of course one also needs to be a little careful with their food intake as well, since even 30 minutes of daily excersize won't compensate for someone taking in 6000 calories a day.

I bought myself a smiths machine which I use in my basement 3 times a week (heavy weight lifting) and I use this to keep myself fit. I also have the Wii fit and play around with this now and then. It's kinda fun really, it is after all a "game" and this alone help keep you concentrated on your fitness which might not work out so well if all you did was some yoga at home on the floor with no extra stimulation to keep you going (But of course everyone is different). The Wii fit has one thing you won't get elsewhere, and it's the "balancing" aspect of the fitness sessions since the board will register minute differences in the way your standing or leaning, and give you advice on how to address (redress?) your stature adequately.

If you've got 500chf burning a hole in your pocket, go for it I say.

I paid 1200chf for my smiths machine and weights... but seeing how gym memberships here in Switzerland are 800chf a year, my smiths machine has all ready paid itself back. The Wii fit combo would pay itself back within 8 months (just make sure you use it every other day at a minimum).