I saw the trailer for the movie before watching it. Did you?
It[the plot] surprised you in some way?
What was so predictable about it though? I mean, did you predict they (or at least one of them) was going to start fucking some dead/demonic girl? I mean that right off the bat was pretty surprising. Did you predict the ending? etc.? I literally had zero idea of what the film was going to be about, so maybe that helped. I don't recall reading or hearing anything about this film going into it.
I also felt the acting was good, the overall direction, cinematography, etc, etc was well done. I think you're being a bit harsh giving it a .5 out of 5, when I've seen you give some pretty shitty movies a 2 out of 5, etc.