This is a movie I would love to love, mainly for confirming what I suspect about nuns all along, that they're Nazis with a serious sadistic streak.
The performances ARE strong; of the generally excellent cast, I'd single out Britta Smith as Katy, the elderly, rather simpleminded inmate, and the thoroughly courageous Eileen Wash as Crispina. And Mullan was good enough to relate the existence of the convent and its practices to the general community, who condone such things happening (or at least condone sweeping girls away into places where such things can happen). That moment when Margaret hesitates before the open door is telling: she knows if she gets out she has nowhere outside to run to. The surrounding community is every bit an extension of the convent.
But it struck me the wrong way, somehow, starting from the moment one of the girls has an interview with Sister Bridget (Geraldine McEwan) and she counts money right in front of her. First, I wouldn't dare count money where someone in front of me could pick up a bill from the desk when I wasn't looking; second, it seemed like a hamhanded way of saying "yes, we're in this for the money," which Mullan suggests isn't true anyway, or tries to.
And I'd like to have seen more complexity in the characters. Were all the girls on one side and all the nuns on the other? I would imagine there was bullying even among the girls, cliques formed, loyalties and enemies made. As is, they had a few spats, and maybe Katy sucked up to her superiors, but by and large they were all united against the nuns. Can it have been as simple as that?