Moria says, "part flower child ghost story, part vampire movie and considerably lacking in explanatory logic, it is nevertheless a film of often unnerving and eerie effect." Classic-Horror.com says it's "a film about insanity, but what makes it so astounding is that it doesn't ask us to study madness, but rather to share in it" and calls it "one of the finest horror pictures of the 1970s".
HorrorNews.net says it's one of Stephen King's favorites and says,
An intelligent script with plenty of genuine scares, a great deal of moody atmosphere, an intriguing subtext regarding 1960s drug culture, and one of the best-ever female performances in a horror film. Let’s Scare Jessica To Death is, quite simply, one of the best ghost stories ever filmed.Slant Magazine doesn't like it at all, closing with this: "OVERALL: Let's bore gorefreaks to distraction." DVD Talk calls it "an impressively creepy little horror film, quite good for such a modestly budgeted work with no stars" and says, "In all departments the film is above average." Dread Central says, "Though it was slow and creepy, it was almost too much of both, which led to an overall dull viewing experience." Rotten Tomatoes has a critics score of 33%.