It is a book not to store on the bookshelf, but have open on your desk while you are coding.
This book is not one of the usual line of programming books, with narratives that teach you about a topic, perhaps show a few examples, then move onto the next topic. Books that you would perhaps sit down and read a couple of chapters of at a time. This is, as the title claims, a cookbook. It is still laid out in chapters, with topics such as 'Workingwith Strings', 'Dates and Times' and 'Associative Arrays', in total 23 chapters, plus some miscellaneous Appendixes. Inside each chapter there are a series of sections (recipes), such as 'Computing Union, Intersection, or Difference of Unique Arrays', a problem statement, a solution expressed as code fragments and a discussion section explaining why the code works and why it is a good solution. It does not attempt to teach you about basic PHP syntax; rather it assumes you have acquired some foundation knowledge from elsewhere, but not yet got to the 'expert' stage.
The bad bits. Some of the recipes are a bit simple, even for new comers to PHP and some of the more complex ones just use an external library, which whilst probably a good solution does not help in understanding PHP. The good bits. Pretty much everything else. There are many excellent examples of PHP and I had numerous 'That's neat' thoughts while I was reading this book.
I think almost all PHP users who are between the 'absolute beginner' and 'expert' stages would benefit from this book. It is a book not to store on the bookshelf, but have open on your desk while you are coding.