I can't believe that so many are comparing this movie to Argento's. His work is far more imaginative and vicious--and a lot more fun.
The director simply lacks the ability to build real tension. The murder scenes--and let's face it, that's what this genre is all about--aren't interesting. It was not hard to guess who the murderer was, and I really didn't care when it was revealed. The cinematography isn't memorable, and the much-praised 19th century Gothic atmosphere just didn't draw me in. Several of the actors are quite good (especially the headmistress and the sadistic girl who lords it over the younger students), but they're given very little to do.
Yes, there are undertones of incest, sadomasochism, and lesbianism, but amazingly, they add very little spice or suspense.
If you're looking for a good horror movie, look elsewhere.