Hiya there is a similar thread to this already and you will see mixed views...
its a good way of doing something when its raining but wont really impact as much as real exercise.
It's really good! Unlike Wii Fit, it actually feels like exercise, and there's a great variety too! Get into a routine of using it, and you'll see results?
I got it last week and the excitement of using it has now been replaced with dread!! Thats only because it makes you work though, it is good for getting you moving, especially for me at my size. I've took up cycling and its great to use on rainy days as touchmytoes said when going out isnt possible. Im only on the easy level and find it hard, but i feel guilty if I miss a day so its good that it forces you to do exercise most days.