The scene illustrates Brown's most important qualities: his indescribable drive as a performer, and his almost blinding charisma. For that, kudos go to director Taylor and producers Brian Grazer and Mick Jagger (yes, that Mick Jagger, who's made no secret of Brown's influence on his own famous moves.) But none of it would work, of course, without Boseman, an actor on a remarkable run of late, playing Jackie Robinson in "42" and now this. The always excellent Viola Davis plays Brown's mother, Susie, but since Susie left her son as a boy, we don't see enough Davis — just a few sad moments from Brown's hardscrabble rural youth, and then one excruciating, wonderfully played scene later, when she comes to see her adult son backstage at Harlem's Apollo Theater. Luckily, there was time for the scene where an older Brown bursts into a meeting at a building he owns, shooting at the ceiling with a rifle; he's annoyed someone used his private bathroom. [...] memorable: the scene where Brown encounters a young Little Richard (Brandon Smith, highly entertaining), and Brown's amusingly incongruous appearance in a ski sweater in the 1965 Frankie Avalon film "Ski Party." [...] we have a portrait that is not uniformly positive — Brown was too complicated for that — yet falls mostly on the kinder side. Get On Up," a Universal Studios release, is rated PG-13 by the Motion Picture Association of America "for sexual content, drug use, some strong language, and violent situations.