If you made a movie that is making $ 544k domestic and a little over $ 1m worldwide it tells you something. There wasn´t much interest in the first place (no, honestly how many movie goers are that? 100-110k maybe?) Anyway, if you haven´t seen it I don´t think you´d missed out.
Yes, the story is - or rather could have been - interesting. I think it is to superfical. [spoiler] You have the innocent little girl that one day sees the monk burning himself and suddenly she went haywire and becomes anti-everything. From there on the story jumps through the years with little explanations or deeper investigation. It´s the father not wanting to give up on his daughter and the mother trying to move on. You could have easily jumped from Merry´s disapearance to the day her father found her because all what happened in between isn´t really meaningful. [/spoiler] I don´t blame McGregors directing, I think he did a good job and since he didn´t wrote the script you can´t lay blame on him for that. I haven´t read the book, maybe it isn´t even a bad adaptation. Maybe the origin is as sketchy.
All the actors did a very good job and it is what keeps this movie above water so that you get through it. But that is just it, you get through it and after the end you just forget. If this was supposed to be a critical lock into that time in history it failed.