A four is generous. This is a mediocre low-budget slasher with poor gore effects (that it inexplicably dwells on, so you really have time to appreciate how unconvincingly rubbery that neck-slashing looks) and dumb characters. The premise is entertaining--a psychiatrist takes a group of patients out to the desert for presumably healing encounter-group-type work--but even by the usual know-nothing standards for such subjects, "Blood Frenzy" really botches it. The characters are all one-note caricatures of various conditions (nymphomania, alcoholism, frigidity, anger management, post- Vietnam PTSD, and what seems to be simply a case of "bitchy lesbian"), and it's ridiculous that anyone would think they could all be treated together. But OK, it's a slasher film, we're not here for realism.
The "name" actor here is Lisa Loring, who plays the lesbian, which in this kind of movie of course means she's a "man-hater" and puts the make on every woman in sight. (She also wears too much makeup that still seems to be perfectly fresh after a couple days' desert camping and various travails...but there I go, looking for realism again.) Hoo man, she is terrible. She starts out yelling and just gets hammier. The other actors are adequate given their silly roles and sometimes sillier dialogue.
You don't expect a lot from a movie like this, but it really does a poor job of building any suspense, delivering shocks, and other horror basics. By comparison "The Hills Have Eyes" is a masterpiece of complex plotting (among other virtues), if we're talking stuck-and-terrorized-in-the-desert movies in general. Why DID I give it a four? Well, you know--we'll all seen worse.
