What I really like about this book is that it is cheap compared to its competitors. The author does not waste paper with wordy sentences that is only meant to take up space to create a 1500+ book to justify a price.
The author explains three things in depth and better than any books I have ever read (and I have read lot of SQL books): Index optimization, query optimization, and locking.
These three topics are usually for advanced SQL developers who must performance tune a complex database. This book is not for the beginners. Having said this, if you want to be a serious database developer, this book will put you ahead of your competition. I highly recommend it to anyone who wants to be or is a database developer.