I've had both the 28/6 Orion (two or three examples) and the 20/5.6 Russar (one example).
The Orion was indifferent. I had my first some 30 years ago when Soviet equipment was cheap in the UK: there was no mystique to them in those days, and they were seen for what they were, lenses for those who couldn't afford better. I'm pretty sure I've had the 28/6 in both Leica and Kiev mounts and was underwhelmed with both.
The Russar 20/5.6 was far, far worse: not too bad centrally at f/11 but pretty awful at all normal apertures and distances. Others have apparently had better examples, but the best work I've seen with them is still fairly dire. Lovely finder, though.
The 28/6 enjoys a modest cult following among young European photographers who don't remember cheap Soviet kit in the 70s, and among Americans who couldn't buy it because of the Cold War. The Russar used to be very rare outside Eastern Europe -- I remember seeing one 20 years ago in Paris, at the same sort of absolute price ($500 or so) that a mint one commands today -- but it was always a collectors' lens rather than a user.
For a usable wide angle a Cosina Voigtlander wipes the floor with either.
Cheers,
Roger