Most critics come away fond of Son of Rambow, and the fondness gathers around the two boys. Bill Milner and Will Poulter are praised repeatedly for unforced, unselfconscious performances, and the slow growth of their friendship is what the warmer reviews hold onto. The scenes of the pair shooting their homemade Rambo sequel, cardboard effects and all, draw the most consistent delight, and several reviews enjoy the 1980s detail as affectionate rather than fussy.
The reservations are about the storytelling. Several critics find the film loses its grip midway, that the later plot turns arrive in a rush, and that the sentiment becomes routine where it had been sincere. The spread is wide. The Hollywood Reporter calls the film poorly made and incoherent, the Los Angeles Times finds it stylish but shallow and never curious about the Rambo idea at its centre, and Digital Spy says tonal clashes waste a strong premise. Even those dissenters concede the boys’ filmmaking scenes are funny.
