Most underrated horror movie ever?

Or at least, one of the most. It's probably one of my favorites, and yet I never hear people talking about it, at least good things. What I think is that the film is just way too arthouse for horror fans, but the horror elements are just too strong for arthouse fans. The same thing goes for films such as Lisa and the Devil and Dario Argento's Inferno, but those two films are still better known, and at least more respected than Blood and Roses. It's a shame that it doesn't get more praise than it deserves, it really should be ranked with the best of the genre.

The theater is like a faithful wife. The film is the great adventure, the costly, exacting mistress