It does have a certain can-do attitude about it, considering it's obviously dismal budget; and some of the plot elements are ahead of its time. But I've never really understood why some consider this something special, other than some particularly scrappy B-movie cheese.
Has its great moments, but they are only moments. Surprised MST3K never got its hands on it.
After years of B horror movies with men in ape suits and a space helmet on their head, actors wrapping giant octopus tentacles around themselves, or go-go girls drenched in animal entrails, this was a return to pure form for the genre...a sort of drive-in schlock version of Jason & The Argonauts meets Curse of The Demon. The Criterion print looks amazing.
Not a great movie by any means, but its DIY spirit is one that should be inspiring to all filmmakers.
Interesting stepping stone in the history of special effects, but otherwise horrendously bad that borders on being pure camp.