Despite it being a cheap Roger Corman produced quickie, there's a strong cast including Erin Moran, Ray Walston, Sid Haig, and Robert Englund (who has been appearing in horror movies for longer than I thought including two once upon a time video nasties Dead & Buried, and Eaten Alive, both worth a watch). The behind the scenes people are pretty good too with an experienced director and writer, plus the then up and coming James Cameron in charge of production design. According to the making of, Cameron already displayed the easy charm and people-handling skills for which he was to become so well known. The film does look good.
The story, as you'd expect, is completely stupid. When the Mystic Master of the Universe (or something like that -his head is shrouded in a glow which is how you know he's the Mystic Master) learns that a ship has crashed on a certain planet, he sends a rescue/recovery team immediately and it's obvious he knows something they don't. Like he doesn't expect them to come back. So they set off, argue a bit, one of them is obviously a spy (or something) for the MM, and fill in a bit of screen time. Then they land, find a few bodies in the ship and set off for this massive building to check for survivors. Inside the massive building the are confronted by things which reveal their deepest fears which include a giant beetle, an alien-looking thingy, in Robert Englund's case -he suffers from low self-esteem- himself, and a giant phallic maggot which rapes one of the women to death. Corman insisted on the rapist maggot against the wishes of the writer and director but when the film came out the scene made sure it got talked about and it is quiet well done in a manner which manages to be horrifying and yet not quite tastless. Anyway, there's a lot of suspense and a fair bit of gore before the totally stupid confrontation between our surviving hero and- Well, you may want to watch this yourself, and I wouldn't blame you if you did.
There is an interesting bunch of extras including interviews with cast and crew and behind the scenes shots.
As I said at the beginning, I thought at the time that it was rubbish but fun.