I quite liked Oculus. Here’s my full opinion on the movie:
Early in the film, you get the impression that this movie is going to be a horror version of Rashomon, with the sister and brother giving equal but mutually exclusive descriptions of the trauma they experienced as children – she believing it was all caused by an evil enchanted mirror, he believing it was the result of more mundane phenomena. The movie does run with that engrossing idea – for about the first twenty minutes; then it decides to dispense with any possibility that there could be a rational explanation behind their childhood trauma and completely goes for supernatural shenanigans.
The movie from there on out is still very good – mixing the real with the unreal and the past with the present rather flowingly – though it does get to be a bit of a mess towards the end. Still, I think the film would’ve been better than good – a true masterpiece – if it had just stuck to ambiguity.