I've got one. It is very addictive. Some people have told me they don't like the negative readings e.g. it telling you that you are overweight or that your posture isn't great. However, it helps to improve all those little niggles so it's not just a nasty pasty.
The boxing is great, as is the step. I was doing yoga everyday but I've been off training for a week due to a back injury.
I have one and I have just started using it and they are brill, not only do you have fun doing exercise and working at clocking up more time on the little counter, it also keeps a chart of your bmi, weight and when you last exercised, so it makes you feel guilty for not jumping on everyday for a few mins, so yes defo go and get one.