I 'thought' that the furminator was wonderful, got loads of hair off and the coat looked good.
However, when the coat starting to regrow, it grew at odd angles, spirals and tufts and didn't lay flat.
It took about a year to get the coat back to pre-furminator condition.
I would NEVER use one again. I now just use a comb and rubber band to maintain my girls' coats. It is much cheaper and does a better job.
I have to stress this is my personal experience and other COLers may have different opinions.
If you type in 'furminator' in the search in grooming, you will come up with some of these views.