Like others have said, it's great IF you use it...
I find it's really good for me. I have ME and so can't really do much (without knackering myself for days) but the fact that I can do three minutes of step every other day, in my living room is great. I can't do any more than that, and because I can do it in whatever I'm wearing means that I do do it. If I had to go to a gym, get changed, and then attempt a half hour or hour class, I'd be dead. Literally, and probably before I got out of the changing rooms (tying laces is one of the toughest things I can attempt - thank god for Uggs!)
Plus then I lie on the settee laughing at my best mate (who I share a flat with) doing all the fun bits I can't manage!
However, I do have an issue...it weighs about 1/2 a stone light, even when we have just re-set it. Oh well! I only use the weight as a guide...the only scales I go by are the ones at class.