I've had one for about a year now, have used it on several different rifles with good success and no problems. It's sitting on a 12-gauge slug gun right now and has held up to several hundred rounds out of it so far, so I am assuming that it is a well-built, durable unit. Windage and elevation adjustments are a bit finicky to do, but at the size of this unit I suspect that can't be helped. I like the fact that its low profile allows for a much better cheekweld than most other red-dot sights, which have a higher line of sight.
My only complaint is that the cross-bolt mounting screw, which is supposed to fit in the slot of a Weaver base, is too thick to do so. It fits just fine on a picatinny base, but if you want to use it on a Weaver base (which has narrower slots) you will either have to file the slot a bit to widen it or dress down the thickness of the bolt. I did the former and wound up with a couple of ugly, disfigured bases on my guns when I moved the sight off of them. But Weaver bases are cheap, so this is just a minor problem. Otherwise I am quite happy with this sight.