There are two words that rush to the forefront of my mind as I think upon 20 Feet from Stardom. The first of these is "pleasant", the second is "safe", and the combination of those two gives, I think, a pretty clear impression of what kind of territory the film looks to occupy. It is the kind of documentary that one watches solely because it looks at people who don't ever get much time in the sun and deserve more exposure; it is not the kind that has anything especially meaningful to say about them, and Lord knows, it isn't saying anything in a particularly insightful or aesthetically complex way.

The unexplored group being studied by director Morgan Neville in this particular case is - are? - back-up singers. Specifically, the back-up singers of the '60s, '70s, and early '80s, people hired by acts like the Rolling Stones, Lou Reed, Joe Cocker, Sting; a surprisingly small cluster of talented women (and a few men) like Darlene Love, Lisa Fischer, Merry Clayton, TΓ‘ta Vega, Patti Austin, rising star Judith Hill. The film sketches out cleanly and efficiently how African-American singers translated the vocal tradition of black churches into a bold new means of harmonizing and layering sound, goaded on initially by the shady producer-exploiter Phil Spector (the story of his treatment of Love plays like something out of Kafka), turned into the basis for a new richness and complexity in rock and pop throughout the '70s, and into the disappointments that hit most of the back-up superstars who tried to hack it as solo artists along the way.

There is a core group of singers - Love, Fischer, and Clayton take up the lion's share of the film's attention - but mostly, 20 Feet from Stardom does terrific work in democratically, generously exploring the profession from several angles, using several different careers to demonstrate different facets of what the back-up singing industry consists of. There is Fischer, who could have had a bigger career if she'd had the drive to be anything but happy and content in her work; there is Clayton, whose solo failure is tinged with tragedy and regret but also a sense of peace that all that was in the past. The film addresses the increasing irrelevance of back-up singers in the age of soulless computer-based music production, the impact of the Civil Rights and Black Power movements on the largely African-American community of back-up singers, the history of music record techniques over the years.

The film is also only about 90 minutes long, which ain't much time to investigate all of these wonderful threads that the movie starts for itself, and it's no real surprise when the film ends up shortchanging pretty much all of them. The effect is something like skimming a Wikipedia page rather than engaging with an in-depth history: you learn a little about a lot of things, and a lot about nothing. Clearly, the film isn't trying to be anything more than a survey of people's lives and careers over a span of years, so we can't really say that it "fails" at something Neville never attempted and doesn't claim to. But it's frequently annoying that the film will introduce some idea that is striking and richly worthy of more exploration, just to glance by it on the way to some other topic that will be nodded at in passing. In particular, the discussions of how the style of back-up singing pioneered by Love and others relates to African-American culture and identity - in the beginning, because of the asides about its relationship to church choral music, and certainly in the middle, when the politics and black nationalism of the late' 60s crops up, an angle on the material that could support its own feature-length documentary - are begging to be explored deeper. There is a rich and deep and thematically dense version of 20 Feet from Stardom hiding in all these underdeveloped odds and ends.

Instead of that film, the 20 Feet from Stardom that we get is, as it were, pleasant and safe. It is a celebration of these women, their talents, and their art; it is a film intoxicated with the snatches of songs performed by these singers, both in vintage recordings and in their willingness to belt out a few bars, still in terrific voice, for Neville's camera. Which, given the singular quality of their artistry, it's nearly impossible to find any of this onerous or unpleasant. Having a film burst out and say, "you know, this is some really great music" is never amiss, particularly when it is some really great music, after all. Besides, the women upon whom the film focuses have lived some fascinating lives, and the stories they tell - Love and Clayton especially - are so full of fascinating and bleak and exciting developments, with moments of profoundest human feeling sprinkled throughout, that the film ends up feeling like a session spent in the company of a gifted, personable storyteller, whose energy and personality make even the most captivating narrative seem more compelling simply because they're telling it.

It's so wonderful to hear these people talk that I can almost forgive 20 Feet from Stardom for delivering those stories and storytellers in the form of such generic talking heads footage. This is a really uncomplicated film, aesthetically: someone talks about something that happened, cut to footage of it from 40 years ago or whenever, there are short clips of people standing around in their home or on the street or what have you, presumably to contextualise their daily life. Neville is not interest in formal experiment; he doesn't even do the thing I just assumed would happen, where we'd hear songs without back-up singing, and back-up singing without songs, to showcase the importance of these women's work to the music they're supporting. Heads and flashbacks, ad infinitum. The film's content can withstand that, without sacrificing and of its robust human interest; but I do kind of wish it didn't have to.