The question that really deserves to be asked of Straight Outta Compton is whether the very real merit of presenting, in the backwards year of 2015, a story of downtrodden African-American men living under the constant threat of police brutality and suffocating poverty who use their intelligence and skill to rise to the very heights of their chosen field on a message pointedly and angrily condemning the systems of repression that have afflicted them and everyone they know, is enough to overcome the very real sin of presenting, in the backwards year of 2015, a story in which violent crimes against women have to be painstakingly disappeared in order to present the most untroubled self-mythologising autobiography possible. I am happy to dodge that question.

Instead, please permit me to retrench to a no less frustrating conundrum: how is it appropriate to tell the story of one of rap's most revolutionary & confrontational groups, N.W.A., in the form of a paint-by-numbers biopic? Why not put even a little aesthetic forcefulness into it? Not to play the "all politically engaged films by and about minorities should be alike" game, but I can't help but point out the existence of a certain Do the Right Thing, which came out during exactly the same period of cultural unrest that Straight Outta Compton travels back to, and includes an iconic appearance on the soundtrack by one of the other massively important politically active rap groups of the period, Public Enemy. That film's approach to engaging with the social tensions around it is to draw direct connective lines between aesthetic radicalism and social radicalism. SOC would much rather be another god damned musician biopic, thank you very much, frontloading all of its interesting style into a misleadingly interesting opening 30 minutes and thence turning into pure genre boilerplate. Politics aren't just nervously pushed aside; politics are avoided with open terror. Even when the material hands politics to the filmmakers on a silver platter. The composition of the roaring "Fuck tha Police" is turned into a full-on Biopic Moment, in which an uncharacteristically potent and terrifying scene of the group members being harassed by mixed-race pair of cops - the most fully-realised and powerful moment of the film by pretty much every measure - is turned into fodder for one of those neat, nice little cuts where you can just about see the lightbulb flicker on as the artist in question comes up with the fully-formed idea for one of their greatest hits.

Blame it on the powerfully average director F. Gary Gray, whose film career continues to consist of the scintillating Friday and then all the things that signally fail to match up to Friday's potential; or blame it on former N.W.A. members O'Shea "Ice Cube" Jackson and Andre "Dr. Dre" Young, as well as Tomica Woods-Wright, the widow of Eric "Eazy-E" Wright. For those three people - all producers on the film - have the most obvious vested interest in taking the potentially gripping story of personality clashes, little hypocrisies, and bleak confrontation with the hell of systemic injustice in low-income, non-white America, and turning it into a shapeless recitation of events that always circles back around to praising the hard-won wisdom of Ice Cube, Dr. Dre, and Eazy-E, while removing founding N.W.A. member Arabian Prince completely out of the movie, and reducing DJ Yella and MC Ren to the status of featured extras.

Meanwhile, the film's commitment to exploding the burned-in racism in the United States and righteously decrying the pervasiveness of police brutality is as tenuous and non-confrontational as the life story of these particular men and this particular place and time can get away with and not totally fall apart. There's an almost palpable sense of relief after the first hour or so, when it turns away from "this is what life in Compton was like for these men" and enter the fallow fields of "who doesn't like movies about contract disputes?!?" Who doesn't, indeed, though Straight Outta Compton's belief that they need to be presented with such unblinking fullness that the running time hauls itself up to a deeply unjustifiable 147 minutes - a full half-hour past the point that the movie enters the bored-as-hell watch-checking phase - is at best misplaced.

So with all that out of the way, at least the film starts well. It starts very well, in fact, and I was certain for a good 25 minutes that, having already beaten the odds with one genuinely good biopic of a musician in Love & Mercy, 2015 was going to manage to produce two fine pieces of cinema from the most reliably staid and mediocre subgenre in modern filmmaking. Gray's directorial style is too burnished for an afternoon matinee at a suburban multiplex to ever really hope that he'd end up overseeing a portrayal of 1980s Compton that taps into any real sense of blighted urban despair, and yet along comes cinematographer Matthew Libatique to fix that with a remarkable collection of images that are, in themselves, artistic and leading in the way they push us towards the characters in certain ways, but which also steadily avoid the ever-present trap of aestheticising poverty. It's dangerous and coiled in these earliest scenes, where the film's tendency to cut off the ends of scenes and skip ahead arrhythmically works in the favor of building a mood, and where the untested young actors are given the most concrete versions of their characters to play. O'Shea Jackson, Jr. is the clear stand-out, playing his father with a surprising and ingratiating understanding of Ice Cube's own absorbing screen energy, while Jason Mitchell's Eazy-E traces the most difficult and interesting arc, mixing a level of innocent idealism into his performance that contrasts with his rough behavior and sets up the closest thing the film has to emotional stakes in the second hour. Corey Hawkins's Dr. Dre is... fine. Sort of generic, but fine.

Anyway, the film's amped-up realist aesthetic as it follows these three young men around, doing nothing in particular, gives the opening act a level of insight and exciting energy that the rest of the movie, bogged down in plotting, comes nowhere near replicating. The first stumble comes when Paul Giamatti comes into the film and accidentally starts giving a performance much too self-assured and layered for him to not blow his relatively untrained co-stars right off the screen, and not even the dead albino mink the hair and makeup department decided to plop on the top of his head can take that away. He's also playing an ultra-trite music manager who is openly kind and achingly sensitive to his clients' needs, but is almost visibly sweating oil, which augurs poorly for where the film ends up heading.

Still, there are moments that work perfectly; there's recording session scene that depicts with a rich sense of humor and character honesty the confusing annoyance of creating art and not the movie-fied cliché of recording music as a steady flow of inspiration, and the early sequences of the group's financial success are shot with an energetic frenzy (it's where we are reminded most directly that Gray was once a music video director, and in fact that is how he and Ice Cube forged their professional relationship) that, at least initially, forms exactly the right sharp contrast with the visual grimness of the film to have preceded it. There's a lot of a good film inside Straight Outta Compton; it just can't survive the dithering lack of narrative intention and grating lack of depth or honesty that swiftly become the movie's dominant modes as it enters its bloated second half.