It seems as though author Creech wasn't quite sure which direction she wanted to go, and this is reflected in the book's style -- sometimes it's written like a play, and sometimes it isn't. It's really two books. One is a delightful, lovely, wise, poignant story of growing up that can help children to a deeper understanding of themselves and those around them. It contains a view of adults that children rarely think of for themselves, and that is just as rarely portrayed in children's books: people in the process of growing and changing, just like children, who weren't always the way they are now, and who have reasons and experiences behind who they have become. It's all about the backstory.
The other is a fairly lame attempt at comedy. One day his brother is injured in football, the next day his sister is injured in soccer, the next day his little brother is injured in ... a choir performance. Ha, ha. None of this seems to have any point. Leo is supposed to be 12, but you would never guess it from his behavior: His foggy innocence makes him seem half that, and his developmental discoveries seem more appropriate to a 9-year-old. But fortunately these sections of the book don't last long, and then it's back to the good stuff, which is very good indeed.