The book description says it well:
Over 110 immediately usable and effective recipes to solve real-world Dynamics GP problems
The book includes 12 chapters of specific, detailed tips to help you use more features in Dynamics GP 2013 and help you get the most out of Dynamics GP.
In addition to covering several of the new features that were added to Dynamics GP 2013, the book covers a lot of less obvious or often overlooked features can be very handy.
Have you ever used Control Account Management to do divisional reporting of Accounts Payable?
Are you using SmartLists to automatically generate Reminders when you log in to GP?
Are you using the Dynamics GP Excel Reports to quickly view GP data in Excel?
Are you using the Reconcile to GL feature?
Do you want GP to warn you if you try and log in with your Caps Lock enabled?
These and many more are covered in detail in the GP 2013 Cookbook.
The Cookbook format is great because it gets right to the point with a very brief explanation of the feature, step by step instructions on how to use the feature, and then a brief note on how the feature works. Often there is also a "There's more..." note, pointing to additional information, or other ways that the tip can be used.
Overall, the book is a great resource, and I recommend picking up a copy of the book, or purchasing the PDF or electronic version.