Unfortunately, this is the type of movie that draws out all those filmmakers who want to weigh in on what the director did wrong. I'm not a filmmaker, so I just sat back and enjoyed this director's efforts.
All the characters were interesting, and I particularly liked the director's decision to cut back and forth between the various players as the narrative moved forward. That choice requires a little more effort on our part, but it's well worth the effort.
All in all, I had a great time, even if I did get most of my anxiety buttons pushed, but that's what happens when a film builds suspense slowly and relentlessly.
If you're the type of person who enjoys most kinds of movies, then you'll enjoy the unusual approach they took with this one, and it has my most hearty recommendation.