Well, that was another resounding "meh."
I think that McCammon writes amazing visual and a wonderful atmosphere. Very well. It has the deep sensations and verisimilitude that I like (and should expect from a World Fantasy Award winner, so no surprise there).
He evokes a very lazy, vintage Southern atmosphere, and as someone who has lived in and/or visited the South for a very long time, I appreciate that.
I loved the characters of the Moon Man and the Lady. They're easily the best characters in the book, probably because they are the most fantastical characters. Which hits us with the biggest problem - they're the most fantastical characters, and they're black. The Magical Negro trope is so heavy it's painful, to the point where it makes me feel guilty for liking them. Thanks, McCammon.
And the downsides:
The whole novel feels like a series of vignettes from the eponymous boy's life, loosely strung together with all of the magic that one feels as a child. Unfortunately it was very heavy handed, I don't think the author could handle subtlety to save his life.
The whole novel is framed by a kind of murder-mystery. Someone dies, and while there's always interest in what happens (mostly through the main character's father's obsession), the story isn't about the murder. The boys fly, they play ball, they deal with bullies, they run into the Southern Mafia (KKK), a triceratops (no, really), a river monster, Nazis (no, really), and they engage in other shenanigans. Nothing normal, of course. There are characters who flit in and out of the story, people who appear and disappear but leave no lasting impression. Even when one of the secondary characters dies, it doesn't matter.
So a bunch of short stories, no characterization (other than some stereotyping), but the landscaping was pretty. Deux ex machinas when needed, and just nothing... lasting.
The one thing that did drive me absolutely batty were some of the similes. This book is lousy with them, and I don't think you can get a page without tripping over a number of them (they're pretty terrible).
The one I couldn't get past without bookmarking, "...the Buick was knocked up onto the two tires on my side and they shrieked like constipated banshees..." No really, he wrote that (and as a note, there were 3 similes on that one page alone). Terrible.
So yay for atmosphere and mood, meh on story, boo on similes, deux ex machinas, disjointed stories and characters, and ridiculousness.