I have one, use it and love it. It works great to remove loose hair. It's not a brush so don't use it like one. I run it over him with little pressure and let it do the work. I can pull a trash bag full of hair off with mine.
I don't use it all the time though. Once or twice a month.
Shop around if you want one. Ebay, Amazon etc. You can get them cheaper than what they want for them at the petstore.
I have also found that people either love them or hate them.