I found it has been exactly one year since I got this book from Amazon, by checking my mark on its cover - Mar. 29 2010.
I would say it deserves an essentially joyful journey of reading it. Unlike "advanced global illumination", this book is quite readable to engineers, research beginners. Everything is engineering oriented - lead by necessary theoretical elaborations, and then a detailed engineering description follows. Coping with beautiful pictures makes it really attracting to readers.
This book covers almost all aspects of a mature GI renderer. If you never tapped into GI realm, this book is for you.
As demonstrated, PBRT is a path-tracing based renderer - if I could finish it earlier, I would never use Radiosity in my thesis (no one is using it anymore - Finite Element Method has been beat by Statistical Methods). You will see the beauty of statics by how probability theorems make a beautiful picture at the end.
In the latest version of this book, several important new stuff has been added in: Metropolis Light Transport, Subsurface Scattering, Spherical Harmonics, etc.
In a word, Five Star recommended!