I've never tried these tables myself, and I have seen people who claim that they work quite well.
But I've also seen that there have been claims filed against companies who sell them for false advertising.
With fitness equipment, sometimes the benefits get exaggerated quite a lot. Maybe it is doing something, but I'm sure it is not a miracle cure. You'd probably be better off using that time to just do a normal workout.
Anyway, I think you should try it if you want to, but don't shell out money for one at home. Try it at a gym first and see if it does anything to tone your body before you commit.