A shame. Four of us went to see the film, and we were all left underwhelmed. The story, which worked well as a novel, didn't quite translate to the screen. In fact, we agreed it felt more like a first draft than the finished item.
The flashbacks to the difficult relationship with the son were a highlight, but the chance meetings with strangers felt forced, and the individual story arcs didn't develop. The crowd scenes bordered on the ridiculous.
From a sentimental point of view, the film did work in places, but as a whole, it missed its mark. A real shame because the central themes are unique and could have been thought-provoking. Read the book. Skip the film.