Groovy is an extremely powerful language yet simple and fun to use. It can be used for simple scripting (like Python or bash) or for building complex application. Run-time speed was used to be an issue, but with each release Groovy gets faster and close to native Java performances. The language is not difficult to learn for someone with a Java background and after a bit it becomes clear that Groovy is more fun and productive than Java, mostly because of the excessive verbosity of the Java language. Furthermore, Groovy has features - such as closures - that allow Java developers to try out functional programming and get closer to languages like Scala or Clojure as well as Java 8.
The book contains a number of recipes that put the language to work in different areas of software development and interesting new technologies, such as JSON/REST, DSL, NoSQL. Also, there are non-trivial recipes that can actually be used in real life development.
Groovy cookbook is definitively an interesting read for developers who are attracted by the “getting things done” approach and are ready to get their hands dirty without much ceremony. The recipes in the book can help new developers to get acquainted with the language and experienced ones to access advanced features.