Satan has great energy, combining the Banlieue exuberance of La Haine with surrealist grotesque horror not unlike Delicatessan. The threat of violence and aggression hangs over the film from the opening scene in a packed club, with its hyper-macho and sexually aggressive young male protagonists depicted in a way that seems like a parody of the archetype (one character even has a dog called Tyson - who also gets sexually interfered with in a scene that is in the context of the film, amongst the least disturbing).
Vincent Cassel (who also co-produced Satan) plays the role of Joseph with relish, creating a vaudivillian monster at his most threatening when being casually racist and misogynist before he orchestrates the inevitable violent and bloody conclusion.
As Geurilla Pen also notes in his review, Satan doesn't really let up long enough for the viewer to consider the possible subtexts of what unfolds, but suffice to say it transpires to be a sordid, near the knuckle and often uncomfortably funny recasting of the Christmas story as urban myth akin to the "guy wakes up without his kidney after sleeping with a good-looking girl he just met" yarn.
Don't watch this in the expectation of the usual kind of horror, it's another beast entirely, which manages to capture the anarchic flavour of French hip hop culture, and stages a gleefully repellent shaggy goat story which sets out more than anything to entertain those with open minds for demented and transgressive extreme films.