Today I have been reading "Haruki Murakami and the Music of Words" by Jay Rubin, one of Murakami's translators. I will finish it before sleeping.
The book is really good and interesting provided you have read all of Murakami's work. I have read all his novels and short stories translated into English (and some in Spanish), so I did not have much problems following the book. Besides, to know what we were talking about was very important to understand Murakami's evolution as a writer and how the different novels and collections of short stories fit in his life.
If you have not read most of Murakami's books, DO NOT READ this book!! It is too early for you. It will spoil many of the stories and books you still have to discover by yourself and you probably cannot grasp "the big picture" the author is trying to put across.
If you have read all of Murakami's books and consider yourself a fan, as I do, you have to read this book! It will throw a lot of light in future readings and will teach you many aspects you just read past in previous readings.
In short, it is a very nice book for those who admire Haruki Murakami's work and want to know and understand more about him and his work.