My feelings about the book are somehow mixed. Basically book is divided into four parts:
- Introducing Grails
- Core Grails
- Everyday Grails
- Advanced Grails
But even if you already have Grails experience don't just skip over the first two parts, because after having some Grails foundation the first two parts become very useful and very easy understandable. Even for me (and I have some experience with Grails) there were useful information and discoveries.
Very good approach in this two parts from the authors is that they have devoted lot of energy to explain how to test Grails application. This is something I should definitely start to do on my own projects :)
The real fun comes with the second two parts - Everyday Grails and Advanced Grails. I have really enjoyed reading chapters from those parts. They are very nice and are really covering lot of skills you will need during real Grails projects.
In the third part authors are explaining how not to reinvent wheel by using number of available plugins. They show you how to fast and reliably put together advance features by reusing already existing functionality. I liked this approach and using it myself a lot.
There are also chapters devoted to workflows, exposing interface to outside world and using messaging.
After finishing third part you have really solid foundation to do some serious Grails development.
The fourth part is really advanced although I would include basic transactional behavior into at least third part of the book as this is probably more everyday grails than advanced grails. The fourth part will explain advance GORM related features, advance usage of spring and something you will for sure meet in the corporate environment - build and deploy process.
Conclusion
At the end I was very happy that I got a chance to read this book. This book will lead you from the beggining to the really advanced features of the Grails. If you are developing with Grails I am very sure you will have this book near you.
If you are just starting with Grails I would recommend, first read something simplier and then come back to this book. I am sure you will enjoy reading it.
And if you want to buy the book you can do it here :)