"Bronson" is based on the real life of a man often referred to as "the most violent prisoner in Britain". "Charlie Bronson" is a moniker the prisoner (real name: Michael Peterson) assumed as a sort of stage name. According to the film, Peterson desired to be famous and went about garnering that fame by perpetuating heinously violent actions against other prisoners and prison guards.
The film is bloody, violent, disturbing, and incredibly effective. Tom Hardy is a powerhouse in the role in every sense of the word. He's an imposing figure to start. His powerfully built wrestler's physique makes the improbabilities of his physical altercations believable. He captures the audience's attention in a stranglehold of a performance, playing straight a role that could have easily turned into an insane human cartoon. Instead we watch a credibly complex sociopathic character unfold who is apparently choosy about upon whom he will wreck his carnage (primarily the heavily armed and numerous prison guards). His mirthless laughter at the beginning of the film puts the audience off-kilter, not quite able to regain balance until some time after the end credits roll. You're never quite sure what Hardy's Bronson is going to do next. He's so pitch perfect throughout the film, it's hard to take your eyes off this living disaster.
The film is essentially presented from Bronson's point of view, which lends itself to some strange storytelling considering his sociopathic bent. Some self-narrated fantasy asides are at first quite bizarre as they're occurring with Bronson telling his story on stage in full makeup. There is a heavy dose of A Clockwork Orange-style cinematography, especially when Bronson is committed to a truly bizarre mental institution. Again, this could be interpreted as Bronson's views of the situation, not how they actually were. There's also an odd measure of homo-eroticism in the film -- Bronson seems to attract the attention of gay men, albeit never has any semblance of romantic reciprocation -- and you'll see more than one fully nude shot of Tom Hardy's man-bits including a scene where he commandeers a male prison librarian to give him a full-body butter rubdown to make him more difficult to handle in the upcoming fight.
I couldn't quite put my finger on whether or not director Nicolas Winding Refn finds Bronson to be a sympathetic character (a little off-putting in itself), but it's obvious that Refn is fascinated with Bronson's complexities. One can't help but feel that Bronson deserves every last brutal beating he receives at the hands, feet, and batons of the prison guards, as he is presented as the exclusive instigator of each outpouring of violence. The last image of Bronson, bloodied and confined in a solitary cage, whimpering like a wounded animal, is bound to stick with you for a while.
Bronson is brutal, but fascinating to watch, walking a thin line that dispassionately presents a violent life without glorifying the perpetrator. It'll most likely make you uncomfortable, but then again, how else would you portray a guy who wanted to get famous by fashioning the persona of Britain's most violent prisoner?