In Russian/Soviet lenses in M42 I have 2 Jupiter-9's (an older and a newer one), a Volna-9, and a Helios 44-2.
Both the J-9's are great optically and mechanically - although the older one has the aperture markings on the front of the lens where you can't see them unless you're looking at it dead-on - not sure the rationale there (it doesn't matter much once you get used to *where* the apertures are, though). The Volna-9 is a 50mm macro, which is fun to use really close up (obviously), but is no slouch as a normal lens either. The Helios, on the other hand, was dirt cheap (US$20, I believe), advertised as "working", which is technically correct, but has seen much better days. If there was a coating of any sort it's gone now, and there are quite aggressive cleaning marks on it. This means it flares in interesting and somewhat unpredictable ways

But, I actually like the way pics taken with it look, so despite appearances (and the aperture ring is very loose), it was a worthwhile purchase.
I also have a few Leica Thread Mount lenses from the former Soviet Union - the Industar 61 L/D (incredibly sharp and contrasty), the Jupiter-9 again (I haven't used it much, though - the J-9 is mostly a portrait lens, and I can't get the parallax correction quite right on a rangefinder to do the close-up portraits I like properly as yet), a Jupiter-8 I haven't used yet (currently attached to a camera in for repair/calibration), and a FED-50 attached to a FED-2 (nothing wrong with the lens, but I think the camera needs some TLC).
Overall, I've been quite happy with FSU lenses, in particular the J-9 for portraits.
I don't think Roger Hicks has chimed in yet, but in a previous thread his considered opinion was that with FSU lenses "the wider, the worse" was the trend based on his own experience. I've never used anything from the FSU wider than 50mm, and I've been happy with that, so your mileage may vary.