This is a good read for anyone new to the area of testing using web technologies. More than just an overview, it takes you from total newbie to a broad understanding of the theory and practices that go into testing full stack web applications, with even some pointers towards how testing practices can fundamentally improve your software engineering ability.
While it is aimed at beginners, it builds on its theoretical foundations, and doesn't shy away from digging in and explaining the technical as the book goes on. Readers who follow the behaviours it describes will be at a solid level of practice by the end of it, and be equipped to take on the dryer, heavier duty books.
This is not a dry reference, it's a book that is meant to be read, and has a loose, chatty tone. Jonathan has peppered the book with his experiences of where theory and reality have crashed into each other, what he learned from these situations, and how they can be handled pragmatically. After explaining a theory, and showing how it works in practice, he takes the time to explain where you probably want to use it, and where you probably should not. He shows how you can think about the problems that these tools and techniques can help with.
(I provided some technical feedback on the book before it was published)