I thought I had already tried almost all hair tools, but the rotating blow dryer brush was still new to me. The tool took some practice before I got the hang of it, but now that I know how to use it, I can actually get good results very quickly with it.
I use the brush when my hair is almost completely dry, then blow-dry my hair smooth with it. Actually, this tool is just the round brush and blow dryer in one. Ideal for anyone who isn't such a pro at blow drying her nice and smooth like me.
I myself have thin, medium-length hair that is quite frizzy and this tool works well for me! I use the smaller brush myself. I do plan to look up some more instructional videos on YouTube, because I can imagine that my technique can still be perfected a bit ;). For example, I read that some people get a bit of a kick in their hair by using this tool, but I don't want to succeed yet.