Ursula K. Le Guin's first Earthsea book, A Wizard of Earthsea, is a real masterpiece of fantasy literature. In my opinion it's one of the best fantasy books ever written.
Ursula K. Le Guin has managed to write an interesting and entertaining story, which appeals to different kind of readers. I think that children and young adults will find this book very good, but adults will probably appreciate the fine writing even more than children.
If you call yourself a fantasy reader and haven't read this book, you should be ashamed of yourself. This book is a classic and everybody should read it.