In “Get On Up, the new James Brown biopic, 32-year-old actor Chadwick Boseman embodies the legendary funk singer in just about every way. He’s mastered his voice — not just singing but also Brown’s normal, energetic-speaking voice — and he’s mastered the moves. Every time he’s on screen, he grabs us by the collar and commands our attention. It’s a performance that goes beyond imitation.

Boseman doesn’t just make us care about James Brown; he makes us passionate about him, excited about him. He makes us just as excited about James Brown as James Brown was about himself.

Here was a man who was simply high on life. He came from a poor upbringing, and yet, for the most part, never let the world get him down.

There’s a scene where a reporter asks him what kind of music he sings; Brown responds that he sings James Brown music. It’s a hokey line for sure, but Boseman sells the hell out of it. It’s one of many moments he’s able elevate himself above the rest of the movie.

It’s an amazing performance, easily one of this year’s best, and the rest of the performances from the likes of Nelson Ellis as Bobby Byrd (Brown’s longtime friend and band member) and Dan Aykroyd as Brown’s manager all do their part in support.

It’s too bad the rest of the movie is so clumsy and messy. Directed by Tate Taylor (“The Help” and “42,” also with Boseman), the movie gets off to a confusing and muddled start, as it jumps around between about five different time periods in Brown’s life. One minute, he’s complaining at random people because someone used his personal bathroom; then he’s in Vietnam, flying to a concert in a plane with one of its engines on fire. The movie then jumps to a press conference, where Byrd is asked how he and Brown met. And, finally, the movie jumps back to when Brown was a young boy, living in a shack in the woods with his abusive parents.

This is more or less the nature of “Get On Up,” jumping back and forth through time to key moments in Brown’s life. Taylor wants to forgo the traditional narrative structure, but at the same time, he wants to keep a chronological timeline, by flashing dates and subtitles on the screen.

However, he abandons that timeline and skips back or forward to another time period, confusing the narrative. To complicate things even more, he throws in the tired “addressing of the fourth wall” gimmick, which isn’t even consistently done.

It feels like a combination of bad scripting, directing and editing. Written by Jez Butterworth and John-Henry Butterworth, the screenplay lacks any kind of cohesion, while Taylor’s direction is somehow tedious and snappy as the picture makes its way through Brown’s massive, event-filled life.

Most of the scenes fail to make any real impact. There may be a few sassy one-liners but nothing real substantial. It’s not just a matter of covering too much material — a common trap biopics fall into — it’s that filmmakers don’t know what things to highlight and which things to omit. Important events and plot point — the fact that Brown owes a bunch of money in back taxes, his abusive nature toward his wife, his stint in jail, the death of his manager — are glossed over.

Tonally, “Get On Up” is a disaster, being silly one minute and melodramatic the next. The only things that are consistent are the musical performances, and as enthralling as they may be, they start to get repetitive after a while.

Perhaps most egregious about “Get On Up” is the editing. The movie cuts and swerves in and out and around Brown’s life like a drunk driver: There’s no consistency or even much continuity. Like the direction, it’s both laborious and quick.

The worst example of the editing is when Brown is in his dressing room after a show. He’s informed that his mother, Susie (Viola Davis), is there, and just as Susie is about to enter the room and have a heart-to-heart with her son, the movie cuts to some other event in his life.

In the end, it’s all a shame because Boseman is truly great in the role. If it weren’t for Boseman, “Get On Up” would be completely worthless.