I love 'em! I've used a Revlon ionic ceramic one and am now using the Remington T Studio one
here. I got it at Target. It's awesome! I use the paddle brush. My old Revlon one was really good too. It just had the ceramic round brushes but it worked well.
I use the hot air brush as the first step when straightening my natural hair, but I'm sure it would be fine on it's own if you're just blowdrying relaxed hair. I used a hatchet style dryer w/a brush attachment during my transition, and I bet the hot air brush would be even better.