If you have to administer a Debian GNU/Linux system then this is the book you need. It explains why things are the way they are, how they are, and how you should use the system.
Although English is not the native language of the author, the text is easy to follow, well written and things are well explained.
This is a book a really do wish I had bought a year ago, rather than waiting until now (Aug 2006). I will have to read this book again, I think it is the kind of book you can learn from on each reading.
The book is based on the old stable 3.1 "Sarge" release of Debian, but does make some forward references to the current 4.0 "Etch" release. The web site that goes with the book also provides full errata and diffs to the "Etch" release.
It is technically slightly dated now that "Etch" has become the stable version and "Lenny" is due out this year, however much of the book still remains valid. The book covers in considerable depth: The Debian Project; Installation; Releases and Archives; Package Management; System Administration; Security; Kernel building; Mixing Releases; Custom Installation; Creating Debs and Documentation Resources.
Every purchase includes a donation to towards the Debian.
I recieved an email from Martin, there will not be an update of the book for Debian 4.0 "Etch". A second edition has been written that covers Debian 5.0/6.0 "Lenny/Squeeze", however it is not yet available in the UK - I do not know about other countries.