How bad is it? It's one of the worst 1980's slasher films I've seen.
Should you see it? Not if you've seen any other film in the genre. Or any other film is available.
A heavy metal musician makes a deal with a female demon that makes him successful with women, with the demon then getting to eat the women. This was the first film David DeCoteau did for Charles Band (these names should be familiar to readers of this blog) and is therefore even more derivative of other films and less obviously homoerotic (though in retrospect, there are a lot of male butt shots). It has the longest opening credits this side of "Bambi Meets Godzilla." The one good scene is a decapitation by electric drill. One might entertain oneself by seeing if there's more lifted from "Halloween" or "Nightmare on Elm Street," but that's pretty esoteric entertainment for this schlock.