I use the ultradot for Bullseye shooting. I initially got one a few years ago because my aging eyes just couldn't foucus on the front sight very well. I also found that no matter how steady I thought I was there is perceptible movement while shooting offhand. Makes ya really work on trigger control and avoid 'cherry picking'. I don't really have any dislikes regarding this dot scope.
I run a DeltaPoint on on of my M4s. Very quick target aquisition!! Dislike; On a serious 'social' gun must also have BUIS....Murphy's Law and all that stuff.
I shoot both eyes open using these sights.
There are less expensive & more expensive systems on the market. Hope this helped a little.