Things I liked: The price. General build quality seems decent.
Things I would have changed: The peep hole the that is drilled in this is roughly cut. The dovetail mount is a misnomer - there's ONE dovetail and that is the piece you can adjust. The other side is not a dovetail - it's a 90 degree angle and does not adequately engage the other side of the gun's dovetail. Put it on a R7 and it will eventually move within 50 shots and then fall off. Put it on anything more powerful and it will be off in a few shots.
What others should know: People kept recommending this aperture. It seems pretty well made except for the fact that it's useless because of the mount design.