Originally posted by Michael Piziak Is it your experience that Soviet lens are well made, since you've had a lot of them - ?
The majority are very solidly built, especially those manufactured up to around 1990. Manufacturing tolerances and finish can be a little variable, and they tend not to feel like the precision instruments from countries like Japan around the same time. You might call them a bit "agricultural". A few - typically later revisions of earlier models or completely new designs from the post-Soviet era - aren't so well built, and can suffer from poor quality control and reliability (one example is the Zenitar-M2s 50mm f/2 - an unfortunate mix of plastic, metal, poor mechanical design and build quality, but rather good glass).
Optically, they're a mixed bag - some are excellent, others good, some OK but nothing to crow about, while others aren't very good at all. Many (even some of the poorer ones) have rendering quirks that can be either a lot of fun or somewhat limiting creatively, depending on your outlook and preferences. Personally, I like the variety and generally find unusual rendering fun to work with.
One thing to consider is that many Soviet lenses have now had a number of owners, they've been well-used over the years and - in quite a lot of cases - poorly serviced, so it can be a bit of a lottery when acquiring them. Buying from sellers with good feedback and returns policies is advisable. I've often gone through several copies of a particular model before finding an example I was satisfied with... but that's collecting for you