Published by Microsoft Press and subtitled 'The Official Guide to the Architecture and Internals of Microsoft's Premier Operating System', this book contains roughly what you would expect; a very comprehensive description of the NT architecture and implementation, as well as its underlying concepts.
The book features quite a few interactive experiments that allow you to explore the concepts yourself. While these are interesting, most of them rely on tools from the Windows NT Resource kit. Most 'professional' users of NT will probably be able to get access to this, but for£36.99 I expect a book to include the tools that are required to make use of it.
That notwithstanding, if you are looking for the definitive printed source on the NT architecture, this book is probably the place to go. If you want (or need) to know exactly what happens behind the scenes of the Win32 API, this book will give you a lot of insight into the mechanics of NT Threads, Processes Memory Management, Security, I/O and File Systems. In other words; everything you ever wanted to know about the internals of NT, but were afraid to ask.
Of course, books like this are quite closely tied to a specific version of a system and I would expect to this book to look a bit dated after the release of Windows 2000, despite a short forward looking section. On the other hand, NT 4 looks likely to be the dominant corporate Windows platform for quite a while yet and a lot of the material should be compatible anyway.