This is a fantastic novel that I read when I was younger. I really enjoyed it back then, and I still do enjoy it.
Let me say that, even though it is a children's book, it can still be equally enjoyed by adults.
The book is very, very fast-paced and with very little filler moments or superfluous prose. Unlike many fantasy books I've read, there aren't any chapters which feel tacked on or unnessecary. From the first chapter, the novel begins with an exciting battle which introduces our main character, Ged.
One aspect which I really enjoyed was Le Guin's use of magic. She introduced a system of magic which was based on names and words, something that Paolini would later use in his Eragon series. Even as a legal adult, I found myself fascinated by her concept of naming something in order to control or conquer it.
It's quite easy to see how this novel may have influenced J.K. Rowling, Christopher Paolini and even Hayao Miyazaki. Some of the concepts and scenes here, such as the use of names and the school for wizards, have been re-created or re-used in other works of fantasy. Even though Le Guin is primarily a sci-fi writer, the influence which the Earthsea Cycle has in fantasy can't be denied. (Note: These are Miyazaki's favorite books.)
Le Guin is able to create a very imaginative and descriptive world which immerses the reader into her beautiful prose. For a children's book, she introduced very interesting and engaging ideas, which become even better in the third Earthsea book, The Farthest Shore.