I have two of these, one lives on a bike overseas. I bought a second one, and it is even better, they changed the material on the strap that cinches the fender to the seat post, and it holds better than the original, and the company then replaced the strap for my old one. Excellent.
This rear fender is very easy to set up and adjust, and offers excellent protection against rear wheel spray. The seatpost grippper stays firmly in place, so you don't have to deal with it sliding mid-ride and exposing you back end to water. The fender itself also detachesre-attaches to the mounting bracket, which makes the fender versatile for changing conditions like a wet ride to work and a dry ride home.
I appreciate the ability to remove and store the flat, foldable portion of this fender in a back pocket (or anywhere else) without removing the clamping mechanism. It's a feature I wouldn't have thought I wanted but I've ended up putting it to use a lot. Smart stuff, PDW, as usual. I'm not sure about durability but if I haven't updated my review, it means there were no issues.
Nearly perfect fender, it's light, effective, easy to change between bikes, and it can fold away for easy storage. Not very theft-proof, but it's survived 4 months of parking in downtown Washington DC.