This book is good at providing WP7 programming solutions to those how-to questions with additional explanation of underlying concepts. The presentation may be a bit monotonous but what matters is obviously the substance which is in good supply. For both style and content, I like Adam Nathan's book - 101 Windows Phone 7 Apps, Volume I: Volume 1: Developing Apps 1-50 - which covers the same subject but with better depth and breadth and excellent presentational style (and part 2 of this book to be released soon and on pre-order on Amazon).
I am the first reviewer of this book and you will be surprised to know that this book is already being replaced by its second edition due to the fact that Windows Phone 7 development platform has undergone a significant upgrade from WP7 SDK 7.0 (on which this book is based) to WP7 SDK 7.1 (aka ver 7.5 code name Mango) and books covering this new technology have a catching up to do. The second edition - Windows Phone Recipes A Problem Solution Approach 2nd Edition - is currently on pre-order on Amazon.
Unless you're tempted by good price reduction for this first edition, get the second edition instead. The coverage will almost be identical except that the new features included with Windows Phone Toolkit (August 2011, Sep 2011) are missing from this book. On the plus side, the Windows Phone Toolkit up-to-date full documentation and accompanying comprehensive code samples are available on MSDN for download (and free of course).