The author covers most of the features of dropwizard which includes creating RESTful End points, Database access, Authentication, Creating views by means of developing a sample Phonebook application.
The book is not an exhaustive guide to dropwizard and may not match the documentation provided on the Dropwizard official site. But the approach of developing a sample application adding features in each chapter might appeal to some readers.
If you are kind of person who likes learning a framework by developing a sample application, then you can pick this book. Otherwise I would suggest the documentation would suffice.