The trouble with this book can be summed up in the Introduction:
This book is aimed at two groups of people: Apache administrators of all levels and Apache module authors. This range of readers means that the book must cover concepts both having to do with programming and with basic configuration. I hope I have accomplished that task in a way the book is useful to both sets of people.
That's a monumental task to take on! Writing a book for each group separately would each take a tome the size of this book. Instead, we cram two subjects into one book without increasing size and get this -- a book that covers everything but in missing detail.
The first the sections start off on the right foot -- an introduction to Apache and how the web works; a comparison of Apache 1.3 and 2.0 with other web servers; configuring, compiling, and installing Apache; and a module overviews, including the MPM modules that handle pre-forking and threading.
After that, the details begin to slip. Sure, you can get Apache up and running with this book. Heck, you can even get it to pull off some nice tricks with this book. It's not until you start dabbling in these "nice tricks," though, that the incompleteness of this book shows through.
For example, while explaining virtual hosting, the author goes over two ways to go about it -- the one-by-one method and mass virtual hosting using mod_vhost_alias. However, he only briefly mentions using a third method, mod_rewite, which is admittedly more complex. The author also spends some time going over security and logging issues with virtual hosting, but at 21 pages, the chapter covering virtual hosting leaves a lot to be desired.
The same goes if you're interested in programming for Apache. Actually, I'm taken aback as to the amount of coverage the author devotes to the programming of Apache. Not because the author goes into greater detail on how the Apache code works than I care to indulge in (which is to say, any). It's because of it's interspersal throughout the book. In the end, this upsets both sets of people -- the administrators that don't want to program and the programmers that don't want to administer.
I guess one could say that this is a "complete reference" in that it covers every aspect of Apache. However, I'd rather have a "complete reference" that covers its subjects in full detail.