I and a friend have one each [though I'm enclind to get a second Saiga 12 for my son]. Love it. As mentioned above, it is dependable and durable, but it was also classed well above the venerable Remington 870 pump during side by side testing when "Deadliest Warrior" pitted the US Green Berrets against the Russian Spetsnazs. It defenitly is an interesting gun to have and use. PUT A PAD ON IT...
Buy It. Saiga 12's were starting to get really hard to find due to importing issues. I believe some of the import issues are fixed, but it is still a bumpy road for the shotguns future. Why wouldn't you want a clip fed AK shotgun, and they are fairly cheap in my opinion.
I do not own one, but ive shot one on multiple occasions and love it. My friend is noticing a night and day difference during his action shoots against normal semi's. Everyone on the range is now looking into them based on how he was able to perform with it. I am just now waiting for my local store to receive one and it will find its way to my gun safe.
I bought a Saiga 12 when they first arrived here. They shoot well, but with a 4 round mag, you're not gaining anything. With a 10 round mag. in it they are very unwieldy. I can use a semi shotgun with an 8 round tube much easier.
This may be a case-by-case basis but my roommate bought one and it seems like it needs a lot of TLC. They are not oiled at all from the factory and it seems like the receiver is shaved more than usual from even light use. It seems like they are made in bulk for profit not quality. It also jams with anything 2 3/4 and I would not advise shooting steel through it. They are, however; fully customizable and are great for the AK tactical look and 12ga functionality. They need to make a 3rd mag for duck season! And a 28in barrel!