I can't even point one positive thing. The musical score has to take the cake.
And btw, I love 70s horror movies.
I don't know how the production company weren't sued for ripping off a Bergman film. Kurosawa succesfully sued when Clint Eastwood remade one of his movies as a western.
Because there wasn't a film like this before--or at least one that received a wide theatrical distribution-- that was was so raw and disturbing. However, I'd say the good acting would be a positive thing.
I also think this film is terrible, from the writing to the acting. The comic relief might be the most poorly executed I have ever seen-- even Jar Jar Binks was funnier than the Keystone cops in this one.
I love horror and the 1970s was a great decade for the genre, perhaps even my favorite decade for it. I was so excited to watch this, but I found it absolutely awful, alternately laughable and contemptible.
As for why the production company wasn't sued, this comes off like a way looser retelling of THE VIRGIN SPRING. I don't think it followed that movie as closely as A FISTFUL OF DOLLARS did YOJIMBO.