I picked one up a few months ago from a supplier on eBay.
Overall, I really like it. If the truck is moving while it's raining, the cover will shed water to be almost waterproof. I did leave the truck sitting out one afternoon during a heavy downpour and saw a little water leaking in through the point where the tailgate edges, cover, and sides of the bed meet, but nothing significant.
The support arms that hold the unit against the rear window in its folded up position work well. They seemed to be too small of a diameter to me, but I have routinely taken hour-long trips at 65mph with no issues.
Installation was straightforward - it took me and a buddy about an hour and half, but I'm somewhat of a perfectionist. I did not install the drain pipes or the extra seal meant for the front of the bed (closest to the cab).
There are 4 little closed-loop hooks that I believe are to attach straps or bungees on if you don't fold the unit all the way up. I tried it once, and broke one the hooks completely off. The other two hooks on the top side are both oxidizing. Not impressed with these.