We saw it last week and were blown away. This piece is all about madness, but the thing that separates it from the vast majority of such films is that the madness has a degree of realistic restraint, and exists in commonplace surroundings that make denying it's existence stunningly easy. The success of this film is that there is no need for the viewer to have been a top calibre ballet performer in order to identify with the young woman. We feel pity for her pat, mundane, timid, bullemic, girlish nature, in the same way we would any insecure young woman, only to find in retrospect that she was indeed very destructively disturbed and motivated. With a few stereotypical "culprits" in plain sight(?), such as the stage mother, the svengali director, and the femme fatale, party-girl co-dancer, we want to believe that others were undermining or even conspiring against her, but... it was all of her own making. The final scene, as she whispers, is indeed "perfection". That moment is the sucker punch of this film, and it is a beauty.
Portman's performance shows that she has elevated herself to mastery of her craft.