My dh and I tried one at a 2nd Wind store. The one we looked at was professional quality and very high in price, plus we don't feel that we need it (yet). I really liked it, as I think it helps stimulate nerves and muscles throughout the body and also probably helps with balance. (For balance, I benefited from using the balance board games on our Wii. Got long-lasting benefits from that.) If your balance is not good, you might want to get one that has handles to hang on to.
There are quite a few reviews on Amazon; would be worth checking out. It's been a year or two, but there were some good Youtube videos for them too.
Edit: Here are some Mayo Clinic comments for anyone who might be interested:
http://www.mayoclinic.org/healthy-li...n/faq-20057958