It is hard to rate a movie that is so bad, but still can be very amusing. The plot itself is a maimed rip-off of many sci-fi movies, but so badly scripted that you can't empathize with ANY of the characters. The atmosphere is so 80s - with all the bad special effects and technology of old, but with all the lack of interest for the quality of movies of new - that it makes one want to puke. The actors are celebrities in their own right, having seen them in so many (average and bad) movies, but their acting is simply horrible. Even the music is standard horror flick. There is nothing in the movie that is good, including the famous worm rape scene, which is the only tentacle rape scene in US movies that I've seen, but which was so clumsily made that it stirred nothing.
Conclusion: get really wasted and watch this, you might get into the whole psychedelic mood that the actors and director must have been when shooting the movie. You will laugh your ass off, as well :)