I have read several books now on COM+ and MTS before it, and I have never quite understood how everything ties together and works together. So I have been stumbling in the dark on this for years. My components work, but I never knew if they worked optimally.
This book changed all that. Finally, it all makes sense. This is by far the best book on this subject that I have read. Every piece of COM+ is explained clearly and with enough detail to get the point across without bogging down the reader. It even answered some difficult mysteries for me such as "Why is the JITA checkbox greyed out for my transactional components?" I couldn't even find an answer for that one on the newsgroups.
The .NET coverage is brief and was probably an afterthought (in that it appears in a chapter at the end rather than integrated throughout the book), but it is enough to get started. I am looking forward to a second edition of this book that focuses on .NET and has all the code examples in C#. Juval, please write that!