I have had the CZ-858 4v model (short chrome lined barrel, folding stock) for about a year and have since put a couple-few thousand rounds through it. I am fairly good about cleaning my firearms, but I have put at least 500 through it between cleanings from time to time without ever getting a jam or misfire (though on that note I have never ran it over or buried it in mud then tried to fire it either).
Unfortunately I haven't fired any of the AK series rifles for comparison, but even with the short 4v model CZ, I can fairly consistently hit a 6" gong at 300 meters without issue using iron sights. I can only assume this would be better yet if I had the longer non-restricted version.
I have had no issues with the magazine release on the CZ. It has always worked for me, and is easy to get at but does not snag on anything. Cant complain there.
The only complaints I do have with the rifle is it's wood-polymer furniture and the folding stock. In the rain, they provide very little grip compared to my other rifles. For this reason, I have the Fab-Defense custom furniture on order. As for the folding stock, in sustained firing, or for someone new to the rifle, the sling loop on the left side, and for a left handed shooter, the hinge on the right, have a tendency to impact the shooter's nose upon recoil if their positioning is slightly off... Minor gripe though.
Overall, the CZ is an excellent rifle. Low maintenance, easy to disassemble and reassemble, user friendly (minus the nose impacting issue...), accurate given the cartridge, light, and low recoil. It doesn't have the range of my M1A, but it doesn't have the recoil either, or the higher ammunition price.