Preston Gralla is the author of more than 30 books (including Windows XP Hacks, Windows XP Cookbook and Big Book of Windows Hacks). He has written technology articles for many national newspapers and magazines.
The title of the book might be misleading. It's more about tweaking Windows and doesn't have to do anything with hacking (e. g. exploiting) Windows.
IMHO this book is a must have for windows8 (Power-) Users. It helps you to get along with all the new features and concepts of Windows 8.
On the other hand it helps you to get some of the good old Windows 7 feeling back to Windows 8 (if you like).
Overall this Book contains 121 Hacks grouped in 11 Chapters of different categories and it is best used as a reference. Some of the Hacks are on a more intermediate level and some are more advanced so that this book is helpful for beginners and power users.
The Book is well organized and has a great Table of Content so that it is easy to find the information you a looking for.
Some Hacks have notes where the author gives further information for the Hack (e. g. you can edit the registry directly instead of using the group policy editor when you don't have the Windows Pro version).
For some hacks he doesn't mention that you need to enable “Show hidden files, folders, and drives” in the folder options (for some Hacks he does).
Sometimes the given Path for a Folder contains to many spaces or a slash is missing (e. g. C:\Program Data\ or C: ProgramData). This won't be a problem for advanced users but maybe a big problem for new users.
You can find more infos here.