I think that this story is harder on adults than children--most children's stories contrive a way to isolate the protagonist child so that he or she can go off and have an adventure. Here, Maniac's parents die before you or he get to know them, and then he stays with relatives in an unhappy-sounding marriage. But then he leaves! I think for adults it is hard to manage the amount of trust he is putting in strangers in order to survive and how alone in the world this boy is--what a sad life he has had! But for kids: thank heavens he got away from his weird relatives (like any fairy tale or Roald Dahl book). He's great--he can take care of himself, he runs fast, he catches footballs, he hits baseballs, he reads, he is so open to the world.
The whole story, which is set somewhat in the past (but not that far), is set up about the myth of Maniac told later. It describes his time in the town as though the story has been passed down by folks in the town and perhaps exaggerated. He appears to be a bit of a superhero, a bit alien, and so his outsider perspective and total confusion regarding the white-side-of-town/black-side-of-town is a great way for kids reading it to consider the topics. It *is* confusing and should not be taken as a matter of course. But it is not, by any stretch, the only thing going on in the story, so it is really a brilliant tale in many ways.
As a parent, I just ached for poor Maniac, alone in this world, so trusting, loving and open. I worried about choices he was making and was so proud of his mench-like qualities. But my son, while he certainly learned some valuable things, enjoyed a page-turner about a cool kid who was able to make a difference in a small town.