My husky is the primary dog I bought this for. If you have ever met a husky, you know it is just a constant stream of fur, in clumps if you can't get it brushed out. This vacuum attatchment works great to get the surface hair off him, though it does not do much to get his undercoat, so we sometimes double brushing with a deshed brush with the vacuum brush behind. The little plastic teeth are great for getting the hair out, without pulling or poking, and traps the hair so it does not fall outside the brush.
I also have a sheltie and an Aussie I use this on, though I don't really see much difference with them, but it does fluff and brush out their long coats nicely. I also had a beagle foster dog I used it on once (she was scared to bits of the vacuum), and even with her short hair I could see plenty was coming off. The attachment worked really well on her coat off the vacuum too. Trapped the hair really well until I pulled it off.
The attachment also works great to get the dog fur off furniture. The bristles are soft and flexible enough they do not pull on the fabric, but still loosen and pull out the hairs.