Have a set on my M&P9 FS and love them. The big orange dot is great for picking up the front sight in daylight and I like the fact the rear is serrated and black as I don't care for 3-dots, dots & bars, etc. as I don't like to distract my focus from the front sight.
Have 'em on a Glock and I think they're among the best out there. I prefer a blacked out rear sight with larger aperture; the front sight grabs attention in any lighting condition, which is one of my favorite features.