I have one on one of my 10/22's. It looks unique, cool and it does work. It let's you use "iron sights" without having to think about sight radius. It is also pretty bright in lit conditions. IMO, it is more accurate than red dots or irons.
Here are the downsides:
- It gathers light from above. In dim conditions, they are pretty useless. Even under a canopy it is a bit of a challenge to see the sight.
- They are expensive for what they are. I got mine for around $100. Too expensive for a little chunk of plastic.
- The mounting sucks. It may look like it mounts using traditional rail design, but rather than having a crossbar and clamps to lock the sight in place, it has set screws! Set screws???! This means it ain't going to work well on high powered rifles or handguns. Without a crossbar to lock the sight in place, it's gonna lose zero.
- Not for quick target acquisition. The way it is designed, it is takes more time than a red dot and irons to acquire a target.
Personally, I would not have purchased this if I knew what the drawbacks were. I would stick to glass or irons.