This seems like one of those gimmicky products that shouldn't actually work, but it really does! Kind of awkward to use, but I love that I can curl my hair as I'm drying it - saves SO MUCH TIME! The only thing I would say is since your hair is being whipped around, it can get a tad frizzy. I'm working on trying different products to see if that helps, but that's the only reason why I knocked off the star. The photo is me after working all day, and it wasn't even that frizzy to be honest. My hair holds the curl as if I used my curling wand or flat iron.
I guess they make an actual hair dryer now which comes with this attachment that clicks into the unit like a diffuser or concentrator would but I like that this one can be used on multiple dryers (and included an adaptor to fit different nozzle sizes!).