Fantastic optics and far better for the price than any U.S. made equivelant. Out to 100 yards it is excellent, the dot, being only about 1.8 MOA covers only about 2 inches of the target at that distance. However for faster shooting the Chevron under the dot comes in handy to get on target quick.
Adjusting the sight takes a bit of futzing, the goal however is to make sure, once the rifle is zeroed, to take the dials off and reset them so that when in the zeroed position, the dials read 0. This way, quick range adjustments can be made.
ZERO TO 50 YARDS/METERS WITH THIS SIGHT!!!!! Why? because you will have a near zero at 50 meters, and a far zero at 150 meters because of the hight of the sight and the trajectory of the round. When this procedure is followed, all one has to do to be dead on at 100 is to turn the elevation dial clockwise until it reads 1. The point of aim now is almost exactly where the round will impact at 100 meters. To adjust for 200 meters turn the elevation dial two clicks COUNTERclockwise from 0 until it reads 2. For 300, 3 clicks counterclockwise from 0 until it reads 3. The same for 400. Realisticly though i would not expect accuracy from this sight out beyond 200 yards. But then again thats not what its designed for.
I personally have the EKP-1S-03M, the AA model with the sunshade. Very robust. The reticle is easily seen even in the brightest of sunlight. You may doubt its ability to retain zero. You woluld be wrong. Every time i have removed it from the rifle it has returned perfectly to zero.
I dont think there are any particular downfalls to the sight. However there is one thing you may not be used to. Because of the hight of the optic, you must use a chin weld rather than a cheek weld. The russians belive this is a better position for your head to be in combat because your head is upright, your field of view better, and you are more alert and aware of your surroundings.
Kobra Zeroing Trajectory table:
www.headsbunker.com/html/article_trajectory.html