The Zenit is probably one of the worst SLRs ever made. Some people seem to like this camera because it is simple and mechanical and i makes you learn to shoot photos. The same can be said about Nikon F, F2, Nikkormat, Pentax Spotmatic, Olympus OM1 etc. I've used all of them. And they have much better quality and useability, Zenit wasn't even the best russian mechanical SLR the Kiev 19 was much better.

Problems:
The main problem with Zenit, is the hard shutter button, the 60% finder coverage (nikon had 100%), the bad mechanical machining (I had three of them all stopped working). If you want a classical mechanical camera to actually use then it's no need to buy a Zenit, you can get a used Pentax, Nikon, Olympus or Canon for a cheap price on the web these days. You will learn more about photography espescially composing with the better finder, and feel the lovely mechanical smoothness that only Japaneese and German cameras had.