This book is almost overwhelmingly thorough, which made it, in my experience, an extremely useful resource in preparing for the Zend PHP certification exam, as well as for learning and daily use. While it's incomplete where the test is concerned-you won't find a listing for "Reflection" in the index, for example-it's a useful reference for most of the material on the exam. All of the built-in string and array functions are described clearly and concisely, with examples of use. PHP installation and configuration settings are laid out in the kind of painful detail expected by the exam. There's an introduction to object-oriented programming, overview of regular expressions and a whole series of chapters detailing some of the most useful features of PHP and reviewing some of the most common problems (web services, user authentication, and secure programming, to name a few). And that's before we reach the second half of the book, providing the same kind of detail for MySQL, including PHPs several interfaces to it.
One limitation, from the perspective of an absolute beginner, is the lack of large-scale examples. Gilmore doesn't walk you through the development of a web application; the book is more of a reference text, using smaller examples to illustrate small, specific topics, with the expectation that the reader can assemble those ideas into usable examples. This was probably necessary to enable the chapters to function as individual units, which is one of the book's major strengths.
Books of this size can be daunting to a reader. Gilmore's friendly, readable prose goes a long way toward making this one approachable, as does the modularity, allowing a reader to digest only the chapters needed at any given moment.