Tense all along I really can't decide what my vote should be for this movie.
It was really tense all along the movie. No matter if they used real bodies or not. It gets my 10 for that.
But the main plot is somewhat nonsense or weak. What is happening, why is it happening, who is doing it, why doesn't this happen when something similar can happen and etc. You get some answers to those but they aren't developed well and remain thin at the end of the movie. It gets a 5 for this.
Overall I think even if it was a documentary, it would be spooky just for the effects, music and the sense of dealing with the dead.
It was more like a movie of atmosphere more than scenario.