Yes, the Soviet color materials were AWFUL - really, even not simply bad. But their Czech, Hungarian and East German counterparts were quite good. Again, they used the older AGFA process, not E6 or C41, because they were intended to development by user, and the chemistry kits were sold for this film. That's why they were not recommended to Westerners - it should have been a pain in back to find this chemistry and someone willing to hand-process this film in USA, say. Soviet photogs were given Kodak for their color work (each sheet and frame was counted, no right to error!) - and there was only one machine in Moscow able to process Western films.
Cheers from Moscow, Zhenya