The movie isn't scary. It's more funny. The TV series is much better, although it is not especially scary either.
I think "Sinister" is scary and also "The Ring" and "The Grudge".
Silly question. Would Buffy The Vampire Slayer be a scary movie to watch on a Halloween night?
For some people, I guess.
But it's nowhere near the gore of modern "horror" movies. More like the "Scary Movie" spoofs.