As I read the admiring comments about this movie, I find myself confused. Yes, this is an excellent documentary -- and the question of whether some scenes may have been staged bothers me less than it does another commenter. Yet, good as it is, this sort of documentary did not spring newborn from the mind of Lionel Rogosian, like Athena from Zeus' brow. There are clear antecedents, like the photography of Walker Evans and even movies like Boris Kaufman's LES HALLES CENTRALES (1927).
In many ways it is a remake of the 1941 Passing Parade short THIS IS THE BOWERY, without the voice over commentary. Instead, it reserves its commentary to its cinematic choices: the editing that cuts faster and faster as arguments rage and the uncredited photographer, who carefully composed and key lit portrait shots that scream "This is a human being", Film is a medium that can lie or tell the truth twenty-four times a second, but which lies or truths the film maker chooses to tell.... that's the real point.
Having thus demonstrated my learnedness and balance as a film critic, let me turn again and note that such issues are irrelevant. A movie is made for an audience, and how would this movie strike its audience, who probably could not recall having ever seen anything like it before? Like a thunderbolt. This sort of cinema vérité film making was something usually seen in post-war Italian movies where the producer couldn't afford a studio. To see it applied to reality in the United States was devastating and changed documentary film-making permanently. At least, until the next new and greatest thing came along.