I've three of them now. A 20-ga, a 12-ga and a 12-ga PDW that I built with spare AK parts and a lot of legal wrangeling on my own. The only one I've ever had any sort of trouble with was the "PDW" as its 10" barrel is too short to reliably cycle light loads. The full sized 20s and 12s are awesome hunting shotguns, and I even shoot traps with the 12 with a spacer in the magazines. Anyone who said they arnt reliable either hasnt figured out the gas system (its adjustable) or is a moron. Its an AK for pete sakes.
If you go to the forums on the Saiga-12 website (http://forums.saiga-12.com) they can usually answer just about any question you've got about the guns themselves. Just put away any thoughts of putting a pistolgrip and an AK synthetic stock on it unless you want to go the MFR rount I went and declair it a prototype for an LEO gun...
If you ARE an LEO you can get the Saiga-12C which is the tactical version, I believe with a 14"bbl and an AK74 style folding synthetic stock, in addition to the 8rnd magazines.