Yes, it works according to most users and it was even voted best product of the year at the Product Of The Year USA awards early this year. The product uses what is known as Thermicon Technology to clear away hair. Furthermore, it is the most popular hair removal product currently on the market.
I own one and it does reduce my hair growth definitely. Like any product you need to use it continuously. I've had laser hair removal treatments in the past and even after 7 sessions I still had some hair left over. I mostly use the no no for facial hair and I can see it's starting to reduce it even more. I've been using it for 3 months and I see a difference :)