I read this book with heavy nostalgia as Oz is my favourite fantasy world, although I had never read the book. I didn't realise there were fifteen books altogether but my boyfriend kindly bought me the box set for valentines day.
I really like the book because it has a real sense of fantasy and wonder, just as expected. I would prefer more detailed writing as I am fond of details in my books but I accept that, as a book aimed at young children, it won't be quite as descriptive as books with a slightly older demographic (like 'A Series of Unfortunate Events' for example).
I do highly recommend it though as it is a classic and, rightly so, is very beloved. Bare in mind that it is quite different from the film in many ways and actually a bit slower at times. The film might even be the superior version in some ways (the way with Judy Garland). Can't wait to read the rest of them!