There are other books on Grails, ranging from the definitive guide to smaller books that show how to build a small application. The advantage I hope my book has is that it shows how to build a realistic application and gives guidance on how to build a Grails application on a real project. I have chosen to show how to use a number of plug-ins rather than going through every single feature of Grails.
Also, because the application progresses incrementally, the reader can see the design decisions that I have made, along with the rational for those decisions as each new feature goes in. The aim being to show the mechanisms in Grails that allow you to reduce complexity as your application grows.
For example, I don't talk much about services, until one of the actions is beginning to get too complex. In the same way, when a GSP starts to become too bloated or is repeating code, that is the time that templates are introduced.
Another difference between other books is that this book, despite the current title, has been tested on Grails 1.1 and shows how to use a number of the new features, including:
This is actually a Grails 1.1 book, it is just that the marketing has not been updated yet!
On a final note, 'better' is very subjective. Some people may prefer a complete reference guide, in which case, there are more appropriate books. I hope this book will get developers who are new to Grails excited about the productivity increases that can be achieved and also arm them with the information and confidence to pick up Grails in a real world setting.