This is one of the first practical books to be published that is entirely Rails 2.0 focused, but its real strength is in the terrific, direct comparisons to how to accomplish the same tasks in PHP. By directly linking specific features, functions, and other programmatic process in PHP to Rails, this book lets you learn something new (Rails) by revealing the similarities (and differences) with something you already know (PHP).
The author is clearly an expert PHP programmer, and while you will certainly come away with an appreciation for the elegance and parsimony of Ruby the programming language and Rails the web application framework, the book is by no means "down on PHP." Indeed, I learned a couple of PHP tricks, that let me do a few (simple) Rails-like patterns in PHP.
In all, this is a terrific book, and if you're a PHP developer interested in learning about Rails, this book is *the* way to do it.