There was nothing wrong with the writing itself, but the author seems to have let the message interfere with the plot and the characters. For instance, the main character's parents die and he doesn't even feel bad about it until about 2/3 of the way through the book. Instead, the scene where he finds out his parents have died is turned into a poor attempt at a joke (that wasn't even funny). The author apparently can't decide whether he wants to be Mark Twain, with his biting cynicism and social commentary, or Terry Pratchett, with his easy-going, make-fun-of-everyone outlook on the world; so he alternates between the two. These two writing styles don't go together, making the social commentary seem forced, especially since it's unclear what he's parodying or mocking most of the time. He gets only about half of his facts about the 30s and 40s correct, and the plot itself is difficult to take seriously because he keeps interrupting it to make more awkward social commentary.
Not a bad book, but not a good one either. Honestly, I think the author was simply trying too hard with this one.