The makers of "8 Mile" say we’re not supposed to treat their film as an Eminem biopic, but they don’t make it easy for us. The Grammy-winning angry white rapper from Detroit takes the lead role as Jimmy (aka Rabbit), a white boy from Detroit with a gift for rapping and dreams of a record contract. This is probably why he puts in a convincing movie debut.

Most of the time Eminem is playing his previous self, a frustrated young man languishing in a dead-end job and living with his chronically unemployed mother, here played by Kim Basinger.

Rabbit’s insecurity holds him back from performing at the weekly "battles" at a local club, where rappers go head-to-head to win the applause of the crowd. The film opens with him "choking" and fleeing the stage from the baying crowd.

It’s a kind of voyage of negative self-discovery – the worse things get (girlfriend cheating, he gets beaten up, etc.), the more Rabbit realizes he’s got to change his life on his terms.

Eminem’s own performance is credible more by screen presence than by acting. He does "meek and vulnerable" well, despite his conventional image as foul-mouthed troublemaker, and this contrasts powerfully with his potent stare and effortlessly intelligent rhymes. At one point he cuts down a buffed-up black guy in a muscle shirt by labeling him "Snoop Dogg in a bra."

Hip-hop is the centerpiece, not just in the electrifying battle sequences, but among Rabbit’s co-workers during his lunch break at the factory, or when he and his friend adapt white southern anthem "Sweet Home Alabama" into a rap about being broke in Detroit.

There’s nothing new here – the movie is pretty formulaic "underdog-makes-good" stuff and adds nothing of substance to that well-worn genre. Eminem gets a simple vehicle to plug his rapping skills and trot out the same life story he’s already told in his music. It’s his manifest talent as a hip-hop wordsmith that saves the film.