The directors of 'The Son', brothers Jeane-Pierre and Luc Dardenne, are together experienced documentarians. This is made explicitly clear in the film's style, which affords the camera the rare opportunity in modern cinema to see rather than show. The difference is immense. Renoir, Ozu and Rossellini understood the difference, and now the Dardennes can be added to that illustrious list.
The Dardenne brothers are masters of exploding the minutiae of everyday life to beautiful, poetic proportions. Their films are largely concerned with observing people at work (see also Rosetta and La Promesse), obsessively detailing the intricate structures and routines of the mundane, the everyday. Hitchcock famously described film as life with the boring bits removed; a Dardenne film is life with the boring bits dissected, investigated and ultimately celebrated.
The film is about all the sons - the sons that were, the sons that are and the sons that will be - and all should see it.