I bought this book and I even got the chance to review the earlier versions to help improving it. It is very well done at my mind. It is easy to follow. They describe the tools and they develop 4 different sample games and they even show how to integrate PhysX into the engine.

The next update of the engine will contain a node based shader editor, endless terrain with a terrain editor, real-time shadow mapping, new collision and a new physics system. This is probably the largest update they ever had.

But the owners of the C4 engine will get it for free, like always. And if someone owns a copy of the new C4 book he will also get the next edition (including terrain tutorials) for free.

I believe that this technology will become the most advanced and powerful indie game dev technology available.