I've also got one in Pentax K-mount, bought from
RuGift in Russia. It looks like their price for the Nikon-mount lens is actually higher than Kiev Camera in the US (to whose auction you've linked), so assuming you're in the US, you might as well buy from Kiev Camera.
Like the others who've posted so far, I like my Zenitar 16mm. Although it's not the lens for all occasions, it's the most
fun lens I've got. As jedrek says, you can stop it down and get huge depth of field, but I often use it wide open with narrow depth of field, focusing on a very near object and leaving the background blurred.
If you Google it, you'll find plenty of reviews, most of which are positive but some of which are negative. The quality control of Russian lenses isn't the best, so be sure you can exchange the lens if you get a dud. I've never used any other lens of this class, so I can't directly compare it to any other. Mine's sharp enough to satisfy me, though. The lens is a bit prone to flare, but I suspect that just comes with the territory -- it's hard to compose a photo on a bright day with a 16mm semi-fisheye lens without getting the sun too close to where it'll cause problems, especially if you want to keep your own shadow out of the photo. I also advise caution with the front element -- it's large and the coating is easily damaged. The lens cap has an unusual shape, so be careful not to lose it. A "lens leash" would be a good investment, but the ones I've seen all have a stick-on bit on one end and a loop on the other -- but a loop wouldn't work well with this lens. I just recently thought of buying two, cutting the loops off, and tying the stick-on bits together, but I haven't gotten around to doing this yet.
Overall, if you want a ~16mm semi-fisheye lens but don't want to spend a small fortune for one, the Zenitar 16mm is the way to go.
