I have a 16mm Zenitar for my Nikon and I love it. Though Ive heard of some problems with the quality control of some of the lenses, Ive had no problems with mine. However, I would suggest buying from an eBay seller who sells a lot of Russian cameras and lenses and has good feedback. I think a lot of people try to pass off broken Russian cameras and lenses on eBay -- Though I see this more with the Kiev 88 cameras.
I contributed some links to some of the zenitar images I have in that photo.net thread linked above. I can post more, if anyone wants. I use it with a Nikon N70 - like it very much, and can't be beat for the price.