I just finished reading this short novel and in the last push I spent two and a half hours on it, scarcely glancing up from the pages. I never do that, but this book is absorbing even though it has almost no "action" in it.
 It's hard to describe it and I can't imagine how it was made into a movie, which was just released, unless it has a lot of narration.
 Readers of all ages will get something out of it, but I'd imagine that the closer you are to the narrator's age—sixty or so—the more often you'll find yourself understanding his observations.