A horror “classic,” starting Wes Craven’s career, The Last House on the Left is not, by any stretch of the imagination, a good film. The cinematography and editing can be generously described as amateurish, the screenplay (a loose reinterpretation of The Virgin Spring) decides that the best thing to play against a harrowing rape/murder sequence is some incredibly ill-judged comic relief of a bumbling pair of cops, and the soundtrack is some inappropriately jaunty country music.
Despite all this, the film is chilling: leaving you with an unpleasant, violated feeling after watching it. This isn’t because it feels particularly real, despite the tagline (To avoid fainting, keep repeating ‘it’s only a movie.’), nor is the movie especially nasty; there’s more restraint than you’d expect in its depiction of violence.
The effectiveness stems from the villains of the picture, four hippies without the pacifism. They’re not Hollywood supervillains (your “John Doe” or Hannibal Lecter) nor are they “crazy” or sketched as normal people who’ve just made bad decisions. Rather, they’re people you could imagine meeting in real life: a little odd, with an sinister undercurrent, who turn out to be genuinely twisted, reveling in violence and rape without forethought or reflection.