Matt
That an author likes to write a book that is well read.
Marli
I suppose it is what you see in them. Probably the struggle and triumph of good over evil. I am re-reading "God, the Devil and Harry Potter". The author, John Killinger, sees much of the Christian message in the series. He thinks they are as great a series of classics as the Narnia series and Lord of the Rings. I think he has something there. I've also read a book that sees the Sherlock Holmes series as the struggle and triumph of good over evil.
Elaine M
If you read them you'd know.
Athena
I do not think the series has an overreaching theme.
It is obvious that if it did, that was radically altered by the events of 9-11.
susan
It's just a really great story. It's a coming of age story in which the main character learns to tell the difference between friends, rivals, and real enemies. Along the way the author addresses racism, bullying, classism, and also gives the reader food for thought about what makes one side more "right" than the other.