This book comes with the author's own 3d engine, and the book itself is like extremely detailed documentation about how the engine is put together and why. This is both a good thing and a bad.
The good part is that he walks through the entire engine, piece by piece, and explains in detail how it works and why it was built that way.
The bad part is that in some sections, you get a very narrow view of how to build that piece of the engine. There are many alternative ways to do some of these things, and they're not explored as much.
Overall though, I find the book very good.