Truth in advertising: if there is anything ssh this book missed, I didn't find it. This didn't feel like a cover-to-cover read, but more of a reference manual where one looked up the info they were interested in. At 666 pages, the reading started to get a little dry after a while - not a problem with the book, I'd feel the same way if I was trying to read through an encyclopedia. The attention to detail is impressive.
This book covers both the commercial ssh and the free openssh. All examples reflect any necessary divergence between the products. The author's extra work will surely be a big help to some, as the 2 products seem to differ on many issues (flags, option precedence, file naming, etc).
This book has earned an 8 out of 10. For an SSH reference, it will be hard to top.