Excellent book! I figured that fellow Nikonians in the earlier reviews may be a little biased and giving it praise regardless - but Darrell, you really did an outstanding job. A nice balance of technical details coupled with practical advice, from someone who is obviously very passionate about photography and the D800 in particular. Your enthusiasm really comes through, which makes you make an excellent teacher for someone like me who shares that enthusiasm and is hungry to learn about the camera.
For any D800 owner who has not yet purchased one - buy this book!!! I have a copy Thom Hogan's as well, which is also excellent, but in a different way. They complement each other very nicely, and I highly recommend you get them both. The cost is negligible compared to value of the knowledge you will gain.
I would also like to put in my two cents and recommend the printed version of Darrell's. As I said in my Amazon.com review, the quality of the physical book itself is outstanding. Being nearly 600 pages in length, I thought this would be a pretty hefty book to lug around, but it is not. The paper and printing are excellent quality; it's only one inch thick; and it easily fits into my camera bag. I like to highlight things and nothing bleeds through the semi-gloss paper. If you're like me and still prefer a "real" book to hold in your hands, you will be glad you got this version.