Another year, another multi-hour Frederick Wiseman epic: and I actually quite liked In Jackson Heights, so forgive me for sounding a bit dismissive. But it comes in a hair short of his last two films, lacking the precision of National Gallery's deceptively dense argument, or the sheer society-encompassing grandeur of At Berkeley, still the best of his films that I've seen. In fact, In Jackson Heights has something I've never seen in a Wiseman film before: scenes that go on longer than they need to.

But who am I to tell one of the all-time geniuses in the field how to go about his business? Slightly imperfect or not, In Jackson Heights is still one of the great American documentaries of 2015, with a timely awareness of society's ills that proves that the 85-year-old director hasn't lost any of his insight into what makes his country tick. The film's setting is Jackson Heights, Queens, New York, one of the nation's most diverse neighborhoods, and Wiseman appears to have set himself to the task of capturing as many of the individual cultures and languages to be found there as his highly depersonalised observational style could manage.

It's a rich cross-section of humanity that emerges, from skin color to sexuality to philosophy. Nor is it an entirely rosy, optimistic portrait: in one of the film's few openly editorial beats, Wiseman cuts from a middle-aged white woman talking about how grateful she is to have the police always there protecting her beloved neighborhood, to a group of transgender Latino women sharing stories about being targeted and abused by those same police.

Still, if there's one overriding feeling that emerges from the material, it's pleasure at the thought this many wholly unique and individual ways of existing in the world can all commingle in one physical place. Wiseman's films, famously, tend to focus on institutions: high schools, mental hospitals, police departments, universities, zoos, always with specific instances standing in for national (at times international) concerns. In Jackson Heights follows the latter half of this tendency: the neighborhood is both itself and the embodiment of something greater. In this case, Wiseman shifts focus to explore, not a human institution, but a concept: what it means to have a community. "The most diverse neighborhood in New York", in this case, is a means of getting us to "a place where many different kinds of people care for each other", and the best moments of In Jackson Heights center on the ways that different individuals and groups act protectively to the weaker and those in need: a traveling prayer group stopping in the middle of a sidewalk to comfort a woman on her way to meet with a dying relative, a support group in which trans women share stories and strategies for coping with the petty meanness of the world, and countless other little moments of one human extending their hand to another. If, in pursuing this theme, In Jackson Heights errs on the side of fuzziness and indulgent editing, those are suggestive more of warmth and affection rather than sloppy filmmaking, for that warmth is the very heart and soul of this movie.