What Works: Suspense. The trailer is immediately interesting because you want to know what happened to Martha. This was a big hit at Sundance, and that's usually a good thing.
Curiosity. I'm curious to see "the other Olsen sister" in action. I'd like to think while she was watching her sisters become so famous she was taking notes on how to act convincingly. She shows more promise in this trailer than the Twin's have in their entire careers.
What might not: This entire trailer sort of screams "Winter's Bone" to me. It's probably because of John Hawkes, who some say gave a great performance in Winter's Bone. He bored the hell out of me, as did the entire movie. That's one of those films that had a very intriguing trailer and then fell flat on it's face in my opinion. I hope the same thing doesn't happen for this for this.
When to see it: It's an independent film so it will probably have a very limited release. When it gets into my area I will try to see it right away before it's gone.
Random Thought: I'm genuinely really interested in seeing this. The more I read about it, the more I want to see.