If you forgive the film its really unlikely and simplistic set-up, then the majority of the film is actually very engaging in what it does and what it allows to play out behind the scenes. The narrative sees a man in his very late 20's who is free of responsibility, suddenly find he has a young son when a former sexual partner suddenly dies, and he is named as the father. This bit requires you go with it, because the core of the film occurs when the boys come round for beers on what appears to be a regular night.
From here the drama is pretty contained in one room, and mostly plays out with banter. The group of friends all talk and joke as they would in real life, but there is a pleasing element to the dialogue where you know that inside the lead character's head all of these same thoughts and doubts have been there already – albeit more in a panicked way. As a result, we get to see the pressure build on Olivier to the point of cracking him. Although he takes it out on his friends, it is his own fear speaking – and this continues as the film ends. This makes the core of the film an honest place, and everything builds off that really well, making it simple and quickly made, but yet engaging and impacting.