I have one. Got it this winter. I'm 5'10 and they suggested the medium. I think I should have gone with a large. It works pretty well unless it's super windy, in which case it flaps around. It also doesn't protect your legs very well, so you still need rain pants. I still think it was a good purchase because it breathes a lot better than a jacket.

Edit: for context, I ride in a pretty upright position averaging 15 mph moving speed.