Pros: Most cats seem to adore it
Cons: Some cats a bit lukewarm on it
Most of the cats previously and currently in my life have started purring at the site of this strange thing, after learning its wonders. The person who first gave me one told me something her sister said, after she gave one of these brushes to the sister.
The sister said "Hey! You melted my cat." (A compliment!) I've purchased these for myself and as gifts.