There's a pharmacy near where I live that carries them. I've tried them once, but at the time all I had to compare them to was depends.... They absorbed a lot more then depends, but I didn't like the fit nearly as well. They also leaked during the night.
Prevails are a decent diaper. Where I live, the only stores you can get them from are medical supply stores. I found that they are alright but are not the best. I would say that they absorb a little bit more than depends. Also, I believe that they all have a plastic backing. Hope this helps.