..oh,so the full version of this book will not be for free?
..anyway,your book is one of the most complete (even though it's not,for now)and informative manual in the 3DGs community,because you have covered almost all the basics of level editing; so i think in the latest chapters you should add tips and tricks on creating more advanced and specific levels/level objects. (ex. RPG themed, Futuristic, etc.)
..keep up the good work!