Based on the novel of the same title by Jonathan Zarantonello, the movie has that novel-y feel. Very character-driven, atmospheric, with dialogue turned just so and loaded with subtext.
Ambush Bug over at AICN says:
- I’m going to tell you right now, put THE BUTTERFLY ROOM on your must see list. It will most definitely be on my Best of the Year list and I feel the need to shout from the rooftops in support of this indie surprise starring some of the greats of the horror genre.
Here's another which offers perspective.