This book, authored by project and documentation leads Fabien Potencier and François Zaninotto, serves as a complete guide to all aspects of Symfony. Readers are guided through fundamental concepts such as installation, configuration, and security, followed by thorough discussion of advanced concepts such as scaffolding, routing, caching, and internationalization. Bundled with numerous tools for helping document, debug, and test your applications, and developed in a manner encouraging agile development principles, Symfony is sparking the imagination of thousands of developers around the globe.
After working in a java-shop for a couple years, even though I'm not much of a Java programmer, I was a little spoiled by the dedication that the back-end developers had to true separation of the Model, View, and Controller layers. When I arrived at my current job, I was a little dismayed by the seeming touchy-feely, free-formedness of PHP. After reading this book, though, I was happy to see that it is very possible to build a powerful site in PHP with a very clear separation of layers.
Great book if you are getting into Symfony 1.X. Back when I read this, I was getting into Symfony 1.4 and I think this book was written for pre 1.4 so some of the examples in the book were different than what I had seen online. Overall though, reading a few chapters really helped me learn Symfony and transition from Codeigniter.