I saw GALAXY OF TERROR when it was first released in the 1980s. It was my favorite of the "top three" ALIEN ripoffs (the other two being FORBIDDEN WORLD and HORROR PLANET, aka INSEMINOID).
GALAXY OF TERROR is a weird film. Its sci-fi mysticism is more STAR WARS than ALIEN, but the sets are certainly "inspired" by ALIEN's H.R. Giger, albeit a poor man's Giger. (This IS a Roger Corman film.)
Others have explained the plot. Astronauts go on a rescue mission to a hostile planet, whereupon they meet strange deaths. Actress Taaffe O'Connell's nude rape scene by a giant, slimy maggot has become something of a cult event.
But what really sets this film apart from many DVD releases is its excellent "making of" documentary. Normally, I hate these things. They're usually just extended commercials (sometimes infomercials) shot when the film was made, to play on cable TV. Everyone just rehashes the plot, and offers obligatory praise (so you don't really know what they're thinking).
But GALAXY OF TERROR's "making of" documentary was shot in 2010 -- 29 years after the film was released. Many of these people are semi-retired, they have nothing to lose, so they can be trusted to tell the truth. Rather then prattling obligatory praise, they sound sincere, and offer interesting stories.
Roger Corman is interviewed, as are MANY of the actors (including Taaffe O'Connell), crew, and New World studio personnel. James Cameron (TITANIC, AVATAR) worked on GALAXY OF TERROR. He's not interviewed, but others discuss his work on the film.
This documentary (63 minutes long, according to the Internet Movie Database) is as interesting as the film itself, and that's rare.
The only fault with this DVD: when I hit the Display button on my DVD player, it won't reveal how long the film or documentary are, or how much time has elapsed. That's why I had to go to the Internet Movie Database to check the documentary's time.