With the first two opening deaths in this movie I left myself wondering if this was one of those "So bad it's good" kinda movies and nobody had told me. And that was a confusion that followed me throughout the entire movie.
The horror scenes themselves are quite silly by themselves, but the rest of the movie isn't. It plays as a serious paranormal thriller and, for the most part it works, but it's ruined by the occasional silly scene. I struggled to find why this is highly regarded as a timeless classic, and the reason most people seem to have is... the atmosphere.
Well... Yeah, I guess? I mean, I liked the atmosphere and the shots and all that, but I didn't think it was enough to give this movie that high of a note.

Also, soundtrack, cudos to you, you're incredibly subtle... www.youtube.com/watch?v=RVAhW4ToLFI