The most affecting, touching and uplifting documentary of 2012 is Searching for Sugar Man, the story of a generation of fans looking for the musician who inspired them.

It's not without its problems; Sugar Man views its protagonist, Rodriguez, through the rosiest of lenses, but it's fun, sweet and the music is great.

The other side of that documentary coin belongs to Beware of Mr. Baker, a movie about one of the biggest assholes—and greatest talents—ever to play music, drummer Ginger Baker.

The first image we see is Baker attacking the film's director, Jay Bulger, with a walking cane, and shouting that he doesn't want Bulger to interview friends or family for his movie. If that's how Baker treats someone working on a motion picture about his life, imagine what the people who really know him have to say.

For sure, there are no stories about the wonderfulness of Ginger Baker the human being in this fascinating portrait. There are stories about his temper and accolades about his playing and musicianship. But the personal stuff? Yikes.

To be fair to Baker, as a kid, he didn't have it easy.

His father was killed during World War II. His mother used to beat him. Baker found a way out of his crap lot in life by getting into drumming. One listen to Max Roach and he was hooked.

Not long after that, Baker got hooked on heroin, and began a decades-long struggle to stop shooting up. Along the way, he played in Cream, Blind Faith, Ginger Baker's Air Force and with Fela Kuti. Baker is largely responsible for making the West aware of African drumming.

Those facts about Baker are mostly known. What's not known is just how often and how badly Baker destroys the good things going on around him. Interviews with his first and third wives reveal the things Baker did to wreck his family life. Most of the time it involves him simply leaving. (Baker talks about nearly everything on camera except his third wife, whom he flatly refuses to discuss.)

More fascinating than Baker's rants—which are the soliloquies of someone with loads of self-righteous anger in reserve—are the stories other musicians tell. Eric Clapton, Baker's bandmate in Cream and Blind Faith, is upfront about his decision to interact with Baker as little as possible. What's more telling is Clapton's mixed feelings about Baker; here's a musician with loads of talent, but Clapton, who seems more inward-thinking than the drummer, can't handle the explosive personality that comes with him.

Cream's Jack Bruce takes a more matter-of-fact approach to things: Baker is this way. You play with him, you deal with him. There are lots of other famous-person interviews, too, including Steve Winwood, Chris Goss and just about every living drummer who felt Baker's influence—from Nick Mason to Neil Peart to Chad Smith to Stewart Copeland and more. (They all agree that Baker's nuts.)

In the end, Beware of Mr. Baker hinges on the man himself, and Baker doesn't disappoint.

He snarls, growls and laughs through his life's stories, and doesn't seem to understand—outwardly, at least—that he's his worst problem. But each time Baker is in poor shape financially, something comes along to bail him out—usually drums. When asked what makes him a great drummer, Baker says, "Time."

His playing on camera is mostly limited to archival footage, and he spends much of the contemporary interview scenes in an easy chair in his living room, taking medication for osteoarthritis and buried behind a pair of dark glasses.

Bulger, after some prodding, gets Baker to remove his shades, and for a moment the drummer looks sad and pensive. Moments later, he's growling again. The kindest word to describe him is "misanthrope."

The kindest thing to say about Beware of Mr. Baker is: See it.

Directed by Jay Bulger / With Ginger Baker, Eric Clapton and Jack Bruce / The Screen / NR / 92 min.