I really enjoyed this book and the writing style. The author takes a concept-tutorial ( cookbook ) approach where he first introduces you to the concepts of selectors, events, animation, etc. and then walks through 1 or more tutorials that show you how to leverage those concepts to add common features to your website. The tutorials are useful, like FAQ's, drop-down menus, Google Maps, Flickr Feeds, photo galleries, form validation, etc. If you follow along with the book and write the CSS and jQuery, you will indeed get a very good understanding of the functionality found in most websites today.
In addition to writing most of your own jQuery, the author also introduces you to a few jQuery Plugins that provide similar functionality. This way you understand the concepts, know how to develop the solution yourself, but also get the efficiency of using available, feature-rich plugins. I agree with another reviewer that these discussions of various plugins can't get a bit long, but often jQuery Plugins don't have the best documentation so this is nice to have for reference in case you do use the plugin for your projects.
My only complaint is the inclusion of "JavaScript" in the title of the book. I believe it is a bit misleading as it only has some basic coverage of JavaScript. It is just a simple intro to variables, looping, etc. Make no mistake that this is a jQuery book. Don't expect to truly learn JavaScript.
IMHO, the book is geared for beginners that want more than the documentation-type snippets you get from jQuery in Action and less visual noise that you get from Head First jQuery. It's a really good cookbook that teaches you the concepts and then how to apply those concepts in the real world in a very easy-to-follow approach. I highly recommended it if you are new to jQuery and enjoy the cookbook style approach to learning without the need of seeing every possible piece of the API and numerous pictures and visuals to understand it.