Finally, I finished this book in the subject of design patterns. It helped me in the subject of design patterns. However, we can not compare it with Eric Gamma's book or Martin Fowler's. They are a must-read not only for every programmer, but for every computer engineer.
Jason Sweat (the author) put a great effort on this book. But TDD programming is overused. You can't get the most out of this book without knowing SimpleTest php|architect expressed this as a feature but in my opinion it is a weakness and not a feature.
UML diagrams are used reasonably and help the reader to understand the subject conceptually.
Appendix A, Pattern Quick Reference is very quick and efficient providing external sources and a brief description about each pattern.
The most important thing you should consider is that unfortunately you can not master design patterns just with reading a single book (Eric Gamma's book is an exception). You should implement the patterns in the real world with a good OOP language such as Java, C# or even PHP (PHP5 and not PHP4).
In my opinion and due to my experience, Factory Method, Singleton, Observer, Registry, MVC and Strategy play more important rules in programming than other programming languages.