If you're looking at this book, you've probably already read all the PBF comics. They're all here in this book, and as awesome as ever. Don't expect too much else though, there's a few unpublished strips (with an explanation as to why they weren't published for each), 2 pages of rough sketches, the interview with David Malaki that you can find online, and 1 paragraph each by Nick and Diablo Cody.
The stuff you can't find on the web is not the reason to buy this though. Buy this because it's a beautifully crafted permanent archive of PBF. The satin-smooth matte cover with an embossed title, the heavy, hand numbered pages with just the right amount of gloss, the red ribbon bookmark, everything about this book just makes it pure class. Your friends will be impressed when they see it on your coffee table. And then shocked when they flip it open.