All of the Harry Potter books are wonderful! They start out being very interesting and easy to read. They change and grow as the characters change and grow. I have read many books, and this series is really just the best one I've ever read. The only other series that comes close for me, in terms of growth, is the Little House books by Laura Ingalls Wilder. Two completely different subject areas, I know, but still the growth of the writer and characters was very fluid.