Wii Fit has been an exercise in smart marketing by Nintendo. Doesn't matter whether it actually makes you fit or not, you call it Wii Fit, it'll sell! Oh, and it'll also attract lawsuits.
Slightly nutty fitness "guru" Michael Torchia has looked at Wii Fit, and as a slightly nutty fitness "guru", does not like what he sees. He reckons that, via "slick advertising campaigns", people are under the impression Wii Fit actually makes you fit, and are forgoing more effective methods of exercise in favour of Nintendo's product.