This movie felt experimental and lacked any real substance, though it did possess some redeeming qualities. I didn’t enjoy this film. It's a production with limited resources, directed by Rémy Belvaux, which constructs a sort of deceptive documentary centered on the criminal and violent actions of a callous and ruthless killer. The premise involves him allowing himself to be filmed as he murders his victims. It resembles an exercise from a film student rather than something intended for general audiences. While it might hold interest for those studying film or writing about cinema, I wouldn’t suggest it to most viewers. There are some genuinely good aspects to the movie, beginning with Benoit Poelvoorde's outstanding performance as the central character; he’s truly the only person in the cast who feels fully realized. The rest seem like background players or simply people required to be present. The sense of realism is striking and occasionally disturbing, and the black-and-white cinematography is exceptionally well done and demonstrates creative direction. However, the film's biggest flaw is a pervasive feeling of amateurism and experimentation that surfaces throughout. It falls into the category of excessively violent movies where events unfold without any discernible purpose or justification. Much of the runtime consists of a series of brutal acts seemingly devoid of meaning. The killer kills simply because he does, and it appears the journalists documenting him are filming merely to have something to film.

Source on TMDB