Grails in action is an excellent book for all grails and groovy developers. It covers all main aspects of grails development and even more. In the same time it does all that within 450 pages. I liked reading the book as its written in a nice and easy English, good style and clear explanations. As other 'in action' books it does set high standard of both language and the content.

I also really liked the fact that there is a chapter with groovy basics, it describes some of the language features very well.

Looking at grails id describes in high details how to develop controllers, views, models and setup the application flow. It also goes beyond that and tries to explain some of the grails mechanics. Authors put a lot of effort to make sure that readers will be able to apply the knowledge in real world. Book shows a set of very useful plugins and extensions that every larger project will need.

Finally book shows you how to test your application code. You will also learn some of the best practices like how to secure your web application against sql/xss attacks.

The only thing that could be described in more details was plugins development but even here authors describe all main features.

After reading the book you should have a fair understanding what Grails is and how you can work with it. Code examples are very good and well thought out, you wont find any foo/bar nonsense.

From my personal perspective its a must-read for all Grails developers. I would even say more, people who work with Spring and/or Java J2EE would benefit from the read as well. It will show you how easy and fun development can be if you let your mind free ; ) I would also recommend this book to PHP developers who are considering new approaches and want to learn new things. Not because its revolutionary but because i believe grails and Spring both have a lot of very interesting concepts and every developer will find here something new and exciting.

Final score: 9/10