I wonder if it was one of the first of its kind to try to explain what it's like to be part of a fundamentalist sect, particularly from the viewpoint of a child. Ninah follows the rules in this restrictive cult, but does not believe them in her mind and heart. She sees what happens outside the cult and wonders why her life needs to be the way it is. And then even more crud happens to her and regardless of whether it was her fault or not (tough to think anything is her fault since almost nothing is allowed), her life takes a turn for the worse.
Reynolds is certainly a good writer, leading you down the path of hopelessness in more ways than one. But the ending? Nope, I didn't like that. In at least a couple of ways it felt forced. I didn't mind that there were many things left unresolved (as befits reality), but I was confused as to why certain actions begot others when any action would have done the trick. In the end, the last 1/4 of the novel felt strung out and then abruptly came to an end.