I got this after reading other reviews, and because it doesn't involve a wii board. After working through the (optional) initial fitness assessment I now have a personal fitness program that is easy to follow and genuinely fun to do.
There's a choice of "venue" and music, as well as the focus and duration of your workout. The trainer also comments and encourages at points during the exercises. If your co ordination needs work, the on-screen trainer is really easy to follow and if you do get lost - hey, there's no one to see!
I've never fancied joining a gym as I'd find their more toned members a bit disheartening. But with this it really is like having your own personal trainer. It isn't boring either as the excercies roll out in a do-able but unpredictable succession.
I awarded 4* for fun because it is so much more than a 'fun game' - it feels like and is a real workout. It was an added bonus getting it for £10.