I found this film entertaining but... not as enjoyable as I expected.
When I first watched the trailer I was excited because the idea was interesting and there were very good actors on board. [spoiler]Nevertheless, the "horror" in this movie, completely blew it for me. If they would have gone with a more psychological damage rather than violent and impossible deaths, it would have had other effect (like, the first one hangs himself right? He might have done it driven to the effect that the art piece had on him, but nope. Then Toni Colette's death happened, and that was way too much for me to keep taking the movie seriously). It looked like a class B movie but with Netflix's budget.[/spoiler]
I agree with all other comments already posted, that Gyllenhaal gave an amazing performance. Feels like that's the only reason that I don't consider this movie a waste of time.