This getting five stars has a lot to do with how emotionally wrecked I feel right now after watching this film. The first thing you need to know is that it's directed by Evil Dead director Sam Raimi. The second thing you need to know is that he's only gotten better since then.
This film has some of the most batshit insane things I've ever seen on a screen, and doesn't even consider holding back on the disgusting things and the perfectly timed jumps. All the while, it keeps a sort of tongue-in-cheek approach to it, which means that sometimes in addition to going "OH HOLY MOTHER OF MOSES!!" you also burst out laughing. One moment in particular will most likely go down as my favourite scene involving gore from any movie I've seen (it's the one involving... er... a heavy metal object, if you watch it). Through all this, the pacing stays spot on in every aspect, and you never feel a dull moment. It toys with you, managing a few times to bring you some jumps that you didn't actually anticipate beforehand, which is a rare feat these days in horror films. Even when you do anticipate them, they're never quite what you'd expect.
Acting-wise, Alison Lohman is so good that I really wonder why she isn't more famous. Much like Bruce Campbell before her, she walks the fine line between horror and comedy with skill, only leaning one way when it'll actually be beneficial. Lorna Raver plays the perfect evil old lady with surprising talent, and Justin Long is, miraculously, not annoying in this movie. All in all, this adds up to what is now by far my favourite horror movie.
Oh yeah, and the last act is genius.
In a sentence:
Perfect pacing, acting, lighting and a mastery of the horror/comedy genre results in a movie that is probably Raimi's best, and thus my favourite horror movie.
