Jessica Chastain's performance is the heart and soul of the film. The audience grows (colder) as Maya becomes more engrossed, and jaded, by her work. She can barely stand through the horrific torture sequences that open the film but by the second hour, she doesn't flinch. Instead you might become more enraged at how frustratingly incompetent our government appears to operate with all the behind the scenes spy stuff. Bureaucratic bungling becomes just as reprehensible as waterboarding over enough time. The film's final act, the raid on Bin Laden's compound, is dazzling. It's edge of your seat film making, which is quite a feat considering the entire world already new the end result (spoiler: they kill him). Director Kathryn Bigelow is an ace when it comes to building tension, and the way she handles all the military and CIA procedural stuff makes Zero Dark Thirty feel more like a documentary than a feature film sometimes, which reiterates just how good she really is.
I don't understand all the controversy the film has been generating. It doesn't promote torture in anyway shape or form. In fact it should be blatantly clear that the film as no agenda or political message behind behind it at all. This isn't go go USA propaganda or an anti-Muslim, pro torture film by any means. There's hardly even any real cohesive plot or narrative in the first place. The film jumps around between a span of ten years, following obsessive compulsive CIA agents damn near spiral into madness to accomplish their mission. Bigelow's film is like a two and half hour Nietzsche infomercial,
He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you....that, and it's a damn fine movie.
(That is, without the doubt, the BEST trailer of 2012 also.)