I have them on three AK's (two just the front). They work OK, but I wish the vial on the rear sight were about half the size. They tend to over power the front as they are. I have a set of Mepros on my 1100, and the vials on the rear sight are smaller and a perfect size. Those vials would be perfect for the AK's.
I ended up putting the factory rear sights back on two of my rifles, and it is really the way to go. With a proper cheek weld, the sights line right up, and the dot is easily seen.
The biggest downside to them is the size (width) of the front sight. Its big, and really reduces the effective range down to about 200 yards. Its not as bad as the one that came on my SOCOM, but it is noticeable when shooting at longer distances. Up close, its fine.
Zeitgeist - The movie
Zeitgeist - Addendum