It gets gamers off their butts, so it's a healthy choice in that respect. It is far from a workout, but I thought that was kind of obvious...
I don't really know how it was advertised, but I used it, and to me it seemed more like a measure of how fit a person was. An interactive scale that could make more observations on your body's overall health, not just its weight, and indeed the game's talking Wii Fit board is exactly that.
I kind of hope the people suing Nintendo don't get anything. Anyone who looks outside of eating right and exercising to become physically fit is just looking to have their cake and eat it too, or in the case, have a healthy body while eating cake too.