Like a true cookbook, this book gives you recipes for how to make certain meals. It doesn't explain every tool and ingredient in your kitchen: that information can be had anywhere.
The authors present several example projects, then go about solving them, introducing you to certain PHP fundementals (and not-so-fundamentals) along the way.
If you are trying to learn PHP from scratch, then maybe this isn't the book for you. This isn't "PHP Cooking for Dummies" ... and I, for one, am glad.