The makers of this biopic on James Brown deserve praise for trying to do something that’s not only cinematically unusual, but reflective of what made its subject distinctive. Unfortunately that very decision is the fundamental reason why “Get On Up” fails as a whole to satisfy, despite its many incidental pleasures

The most obvious of those pleasures is the performance of Chadwick Boseman, who follows up his turn as Jackie Robinson in “42” with an even better one as Brown. Of course, playing a wild, flamboyant character like the singer is bound to be more eye-catching than personifying a more controlled, recessive one like the ball player, but it’s not merely the exuberance the actor invests Brown with that’s extraordinary. He captures Brown’s multifaceted character, from his onstage brilliance to his offstage surliness, and everything in between. (Boseman is also able to mimic Brown’s vocal delivery expertly—not so much in the actual performance recreations, in which the voice we hear is Brown’s, but in the dialogue. Given Brown’s habit of slurring his words, however, that means that what he’s saying is sometimes difficult to decipher.)

And though the others listed as stars are Viola Davis, as the mother who abandons Brown as a child, and Olivia Spencer as his aunt, a brothel owner who takes the boy in when his father joins the army, their roles are actually quite small. After Boseman the cast members who make the greatest impression are Dan Aykroyd as Ben Bart, the manager who helps Brown become a solo star and remains loyal to the end, and especially Nelsan Ellis as Bobby Byrd, whose family effectively adopted Brown after his first stint in jail and who formed a group called The Fabulous Flames with his young quasi-sibling and remained at his side for many years until a cruel slight finally drove them apart. At many points in the film, Byrd serves as a kind of audience surrogate as we witness Brown self-destruct, though elsewhere writers Jez and John-Henry Butterworth and director Tate Taylor have Boseman speak directly into the camera to offer his justification for what’s just transpired.

While the relationship between Brown and Byrd is at the center of “Get On Up,” however, it’s presented in such a fractured way that at one point they apparently break up (when Bart and record impresario Syd Natham, played cunningly by Fred Melamed, invite Brown to go solo), and shortly afterward are portrayed as together again, although there’s no indication of how they papered over their differences. That’s characteristic of the entire movie, which lurches forward in fits and starts, shifting chronologically without warning into the future and then back again. It begins, for example, with the notorious 1988 incident when Brown shot up a strip mall and then led police on a high-speed chase, resulting in his arrest and incarceration. It then abruptly shifts to the USO trip Brown and his band made to Vietnam in 1968, before turning to his hardscrabble rural South Carolina childhood with his mother and father (Lennie James). It’s a pattern—or lack of pattern—that the film will continue to take, shuffling events from the various stages of the singer’s life like the cards in a deck.

But it’s not just the years the film toys with; it’s a matter of styles as well. The initial sequence is like a raucous comedy with a touch of “Smokey and the Bandit” to it. The Vietnam sequence is even wilder and more extreme. Then the South Carolina material takes on the quality of rustic soap opera, all in exaggerated colors and emotions, with the images bathed in glowing auras. Later episodes will assume the form of straight drama (as when Brown abuses his wives or has confrontations with his band members) or goofy comedy (Brown’s encounter with the up-and-coming Little Richard, played with over-the-top flamboyance by Brandon Smith) and sentimental journey (the reunion with Byrd after years of estrangement).

The rationale behind this scattershot approach was probably to suggest in structural terms the mercurial nature of Brown’s personality and the wide spectrum of his experience, and the studied disorganization does mitigate the chronological predictability endemic to most biopics. But while the result is defensible in theory, in practice it’s often confusing, and in the end it detracts from the picture’s cumulative effectiveness, even though it allows many of the salient events of Brown’s life to be plugged in at will. (Curiously, race is an issue that isn’t raised much, apart from a strained comic episode featuring Allison Janney and John Benjamin Hickey in what amount to cameos as a couple of motel guests.) The problem is alleviated, of course, by Boseman’s energy and the superb musical recreations, but it still leaves one wishing that the script structure had been reconsidered.

The approach makes it difficult to assess Michael McCusker’s editing, but within the scope of Taylor’s stylistic choices the other technical contributions—Stephen Goldblatt’s cinematography, Mark Ricker’s production design, Jesse Rosenthal’s art direction, the sets designed and decorated by Rena Deangelo and Jim Truesdale, and Sharon Davis’ costumes—are first-rate. Among the cast, Davis is given too much leeway (especially in the scenes in which she reconnects with Brown after a long absence), but Spencer is allowed more restraint, and Aykroyd does a typically genial turn. Aside from Boseman, however, the standout performance is certainly Ellis’. He convinces as the man who’s happy to stand in Brown’s shadow for many years, even selling as effectively as possible the dubious proposition that other people should be willing to put up with the singer’s outrages because he’s a genius, and geniuses shouldn’t be bound by rules that apply to others, should they? Nietzsche would be proud.

Though it spotlights a great performance this isn’t a great musical biography, largely due to the splintered nature of the storytelling. But there are so many good elements in it that it’s a close call.