I must admit I read the reviews first, and was hoping for more than I got. The premise is pretty awesome - kind of like Alien without the graphic effects. There was an old sci-fi movie from back in the 50s called "The Creeping Unknown" which was a similar plot.....spaceship returns to Earth, two astronauts missing, and the third catatonic. No explanation given, which made it all the creepier. I believe Val Guest was the director and Brian Donlevy the star.
Some stories like this make me think of David Cronenberg - his technical abilities aren't quite up to the level of his ideas.