Every technical book should be like this one; having written a few myself, I know that's a tall order. "jQuery in Action" is concise but clear, humorous but not silly, and answers all the questions it raises, quickly. The reader is never left wondering "But what about..." for more than a sentence or two. The authors clearly gave a lot of thought to pedagogy, because things are explained in a clear way which progresses naturally from chapter to chapter. Factor in the extremely readable style and the handsome diagrams, and it's easy to see why reading this book is a sheer joy.
For each major feature of jQuery, this book provides a "Laboratory page", a kind of interactive HTML playground where you can try the feature out using different options. The remarkable flexibility of these pages is a testament to both the power of jQuery and to the imagination and creativity of the authors.
Perhaps the most commendable feature of "jQuery in Action" is its unflinching honesty. Too often authors are selling you on a product, and they'll gloss over rough spots to win you over. These authors don't do that. They present their topic as it is, describe its merits, and let the reader decide.