This is a truly excellent book. Written by the person who headed up the largest Windows 2000 deployment (in Europe) to date, it not only covers the 'What' of Active Directory, but the 'How' and 'Why'. This includes not only the technical aspects of Active Directory but also the operational and business aspects that are all too rarely addressed in this kind of book,<consultantbabble intensity="religious fervour">but that absolutely have to be dealt with if any kind of ROI is to be realised from this technology</consultantbabble>.
If that isn't enough, the last part of the book shows how to roll your own scripts for adding users, querying the Active Directory etc.. Or as I prefer to think of it, repetitive tasks that you don't really want to go near the gui for. I have this book down as having 585 pages of solid fact, no filler, all examples kept short and focussing on the point in question.
This is an example of how technical books should be written - lots of hard fact with unambigous examples in a well-written style. If you have to go near Windows 2000 & the Active Directory (and I suspect one or two people may be in this position) then buy this book.