AK sights are not the best.
The front sight is a round pin. This is the same type of sight the earlier AR and M16 used.
When the rifle was upgraded, they changed to a square sight so as to always have the eye focused on a flat face, instead of a round pin that reflects light and doesn't give a sharp sight picture.
The rear is the standard European type of non-windage, coarse elevation adjustment-only notch sight.
It's been long known that the barrel-mounted notch rear sight is the worst type sight, due to how the human eye works. While notch sights are the best for pistols, they are the worst for rifles.
The eye cannot focus on more then one thing at a time. Therefore you either see a nice sharply focused front sight or a focused rear sight.
The human eye CANNOT see both at the same time.
When sighting properly, the FRONT sight should be where your eye is focused.
This means the target will be blurry, and the rear sight will be blurry.
With a notch sight on a rifle, you have to continually change eye focus, from front to rear, to keep sight alignment, and this makes it slower and more difficult to use.
The situation is MUCH worse for older shooters, since the eyes begin to loose flexibility of fast focusing and if you're near sighted, the sights will both be blurry.
Peep or aperture sights are the best, which is why virtually every military rifle in the world now uses them.
The rear aperture is looked THROUGH, and the eye focuses on the front sight.
The rear appears to be a ghostly blur, thus the catchy new name "Ghost Ring" sights.
Since the eye only has to focus on one thing, the front sight, the sights are faster and easier to use.
In addition, the aperture rear tends to "Fool" the eye by making the front sight appear more sharply focused.
Target shooters take advantage of this by using an adjustable aperture device that fits on eye glasses.
By adjusting the aperture, the sights can be made to appear sharper and more defined.
The AK sights have only coarse adjustments for elevation, but fine sighting-in adjustments are possible by using the front sight to fine-tune the rifle for you.
Since few people shoot the AK at ranges much over 100 yards the lack of fine elevation or windage adjustments are not that important.
If the AK was a design intended for high accuracy, the sights would be totally inappropriate, but since it's a close range battle rifle, the sights are not as limiting.
So, bottom line, the AK sights are poor, but quite usable, especially if you're young and have good eyesight.
They are not as fast to use, or as precise as modern aperture sights, and the sights are one reason the AK has a reputation of being an less then accurate rifle.
Since the sights and trigger pull are major contributor's to practical versus mechanical accuracy, bad sights give lesser accuracy.