This is a very well-known and popular portrait lens from Russia. The lens does not have an automatic aperture, so it works like a pre-set lens (which some users find a little cumbersome, but once you get used to it, it is not a big problem). The iris consist of 15 blades, so it remains almost perfectly circular when stopped down (see below).
You read contradictory reviews on the internet about the optical quality of the lens. Some report it to be excellent, others find it relatively mediocre (I think there porbably is quite a variation in production quality). I tested my lens and I was lucky to find an excellent sample. Center sharpness is already very good wide open, and stopped down to f/4 and beyond, the quality becomes really excellent over the entire frame.