Meryl Streep = A.
I'm going to preface my comments on Streep's performance by saying that this is Streep at the top of her game, which is sort of redundant; you hand Streep a great script and character and you're guaranteed a great performance. Which is exactly what she gives here. She haunts the movie from the first frame and her presence lingers even throughout those few scenes where she isn't presence, you feel she could be lingering under any one of the many black habits seen throughout the film. I have no Cherry Jones with which to compare, so I'm judging the performance on it's own significant merits. Occasionally Streep is a bit too forthright, though never hammy; you genuinely believe that this is Sister Aloysius just losing her grip on the situation just a little whenever she yells. I give immense credit to Streep for not simplifying her character as the final scene attempts to do, she layers Sister Aloysius with her trademark knack for a character tic and movement; you see the both the compassion and irritability when she gives Sister Veronica the fork, she refuses to embrace one part of the character while excluding the other. A full-bodied and perfectly aligned performance from an actress that has been at it for three decades.
Amy Adams = A-.
In the space of three years, Adams has reinvigorated herself from an actress of an insane amount of charm to hold up a character to a talented actress with a knack for playing doe-eyed innocence. However, to dismiss her performance as being similar to those in Junebug and Enchanted is an immense disservice to her performances in those, which were completely different plays on somewhat similar characters, and an insult to this performance. Yes, Sister James is an innocent nun, but she's not a pushover. Adams imbues James with a noticeable spine and individuality that breaks away from the innocence, she stands up to Aloysius in a way that Father Flynn doesn't even succeed at; she attacks what may be at the core of Aloysius' accusations. I don't blame Adams for the odd scene in which James tries to assert herself in class, but she tries her best to make it believable. Still, Adams turns in a performance of clarity and believability where she could have quite easily glided on her natural gifts.
Viola Davis = A.
I don't know what I can say about this performance that hasn't been said. Davis throws a massive wrench in the workings of the film with a completely heart-rending performance, that tugs and flays at any certainty that you may have had while watching the movie. Davis conveys the moral dilemma within Mrs. Miller, but also the guilt that she clearly has in seeing that, the self-inflicted ignorance. It's an incredible role that Davis gives an incredible reading of. She's breathtaking and powerful, nearly taking her scene away from Streep. An Oscar win would not be amiss.
Philip Seymour Hoffman = B+.
I don't like Hoffman. I know this much. I don't think he's ever given a performance which is in service to the film; he serves only himself as an actor, grabbing every scene and holding the camera so that nobody else gets a fair shot. How Keener managed to get a nomination opposite his most grabbiest performance is something that I won't understand. However, I find Hoffman to give a very delicate, if not particularly subtle performance. He's never actually quiet, even in scenes that might call for it; the scene in the gym. He's always acting and everything, but I think that works for the character of Father Flynn, he's constructing himself as a priest, a teacher, an opponent to Sister Aloysius, a friend to Sister James. It's a very canny performance of the most difficult role in the film; he has to inspire doubt without particularly asking for it. He never quite steals his scenes away from Streep, and there are certain moments during their more heated scenes where he achieves quite a tortured and genuine expression of hurt and hopelessness. My favourite performance by the man, who really needs to do this kind of subtle character work more often. (In saying that, I feel that the role would have been served by somebody who could have inspired doubt much easier. There's something inherently misanthropic about Hoffman that I couldn't get past even from the first scene.)
All The Little Actors - There's a lot of names to look up here, but I felt that all the little bit actors did their part well, sometimes making Shanley's sometimes hamfisty symbolism that more profound and heartfelt. Special notice to the boys who may or may not be overlooked victims of Father Flynn; aptly played reaction shots without being obvious about it.
Overall Film Grade: A-B. I flucuate from day to day.