I have an Ultimk on a couple of my AK's and like them very much. I think the biggest advantage to them is, they allow you to mount the optic fairly low and up front out of the way, of both your field of view and handling. With the red dots, depending on what your using, you may be able to also co-witness the iron sights to the dot. I can do this with my Tasco and BSA dots on my SAR, and I probably could with my Aimpoint on my AK103K if I use a different ring or mount. Most of the lever mounts for the Aimpoint are set up for the AR's and even without the riser are just a little high. I can see the iron sights if I use the 400m setting, but it really doesnt matter as the Aimpoint is on a Larue lever mount and pops right off. You can also use a Scout type scope if you dont like dot sights. I've shot the Kobra's and some side mounted scopes and didnt like them at all. For one, most all of them are big and bulky and sit to high, at least for me, and are not comfortable or natural to shoot with. They are also tend to be in your face and block your field of view. With the lower mounted forward sight. you can shoulder and shoot very naturally, basically just like your iron sights and do so very quickly. Fast snap shots are a breeze and you can get good hits on targets at 100m or better shooting like this. Up close for fast shooting its even better. Another advantage is, you dont have to remove the scope or mount to get to the top cover for cleaning. If you use good quality mounts or rings that hold zero, you can easily pop the sight on and off or switch them at will. I've heard some of the side mounts hold zero well and others not at all. I've also heard a few complaints of the rails not being right or some mounts not being totally compatible and either the scope wont go on at all or cant be zeroed.
Here's my AK103K with the Aimpoint on it:
This is a target of 2 second snap shots from a low ready at 100m(LT) and 50m(RT):
These are 100m offhand slow fire:
These were shot with both my SAR and AK103K. I'm pretty sure the snap shot targets were shot with the SAR, but its been awhile and I'm getting old and CRS is setting in.
AK's are capable of much better accuracy than a lot of people will give them credit, especially if you use a dot sight or some sort of optic. The iron sights work well enough to, but as you get older, they do get a little harder.