The bulk of the Soviet material makes a pretty decent space opera. The savage reptiles are a bit hokey, but the robot and the flying car are actually pretty neat. The Domergue/Rathbone inserts are not intrusive - surprising how well they fit, but I suppose that's the kind of thing they were good at.
I understand there is another version, Voyage to the Planet of the Prehistoric Women, with Mamie Van Doren and a bunch of bikini girls padding the film instead of Faith Domergue, an early directorial attempt by Peter Bogdanovich. It's in my DVD queue, but I don't know if it should be.