Somehow I never read this book as a child, though like most people I saw the musical several times. Reading it as an adult, it's easy to see why it became a classic, with memorable themes and imagery and quite a nice writing style. Listening to it on audiobook, it had a lyrical, fairytale-esque quality which I enjoyed. 

However, while I liked the overall plot of the book, individual events often felt a bit rushed and Dorothy and her friends overcame most of the obstacles they faced far too easily and conveniently. Perhaps if I had read the book as a kid that would not have mattered to me, but as an adult it was very blatant.