Sounds very promising. Actually...much more than promising....more like flat out amazing.
I know what people are saying about Hoffman, since he usually plays creeps, but in the film, his performance doesn't skew it either way. There are moments where you may feel he's guilty and moments when you'll feel he's being senselessly persecuted, which is as it should be. Don't worry about Streep, Adams or Davis either. They are all fabulous.
The film has the same feeling of mounting tension as the play did. I was also gripping my armrest during Viola Davis's scene, since she plays it very real and raw.
For the Hoffman worriers, again, I tell you that the character's innocence or guilt is not betrayed in any way by Hoffman's presence or performance, and there are a few new scenes and moments, including some interaction with the boy, that leave you further conflicted.
The film is opened up in the best possible sense. Nothing feels extraneous, but you see contrasting scenes of the priests and the nuns in their respective worlds, as well as scenes in the classroom with some of the other children that were referred to in the stage script, such as William London, and the girl whom Sister Aloysius wants seated away from the boys. (I'm blanking on the name).
Streep's Aloysius is ferocious. She's funny in the terror she provokes in others and in the character's dry wit, but without any camp creeping into her performance. She's mesmerizing in her stand-offs with Hoffman, and in the heat of the confrontation scene, did something incredibly surprising, giving Aloysius a moment of vulnerability that helps humanize her for the final scene. I don't want to spoil it for anyone. I think it stands with her great performances.
I should have mentioned Adams. She fares very well throughout - and looks great. As you mention, she is the one that hears both points of view from Sister Aloysius and Father Flynn and her reactions are important as a barometer for the audience. I particularly liked her courtyard scene with Father Flynn and her standoff with Aloysius where she defends the priest. She also benefits from some new material in her classroom, where she tries to adapt herself to the methods suggested by Aloysius, and a moment where she witnesses something that further clouds the issue of Flynn's innocence or guilt.
I don't think Streep's qualifications to play the role would ever be in question. Nor is a comparison between Cherry Jones and Meryl Streep's interpretations quite fair. Film, by virtue of close-ups and editing, can do things that theatre can't, and by comparison, the electricity of live theatre when it is at its best, is a sensation I do not usually experience even at the finest movies.
If I had to compare the performances, I'd say this: for me, Cherry's Aloysius seemed absolutely resolute in her conviction until the play's final scene. Streep seems to allow some consternation and vulnerability creep in starting with her scene with Viola Davis. Both Aloysius performances are equally forceful, terrifying and imposing - and funny.
As for other questions about Shanley's work as director, I don't think it is my place to "grade" his efforts (I leave that nonsense to pop culture magazines), but it is simple, unfussy, generally clean and direct, without calling attention to itself. Since Shanley grew up in the Bronx at the time Doubt is set, he also knows the neighborhood and the look of the film feels right in its production design and attention to detail.
Regarding the other characters that were in an early screenplay, apart from a few shots of William London (the one who "would set his foot on fire" for a day out of school) and a boy who is sent to see Aloysius after talking out in class, there is no material in the cut I saw examining the "mental growth" of the other boys.
The movie ends as the play did. I think the film is a much better translation than either The History Boys or Proof. The quality of all of the acting is very high and I had mentioned earlier that I think Streep's performances stands with her finest work.