.NET, unlike Java, is an implementation of an ECMA and a ISO standard.
This book, from the Microsoft employees that created .NET and with input from members of the standards bodies, annotates the standard with comments that provide insights into the reasoning behind the standard. If you are in one of these categories, you should seriously consider buying this book:
1. advanced .NET developers
2. language designers
3. tool designers
4. those interested in understanding virtual machines
5. developers of libraries
6. Java developer (wondering what a standard looks like, just kidding. As an intermediate-advanced Java developer, the book is very interesting though.)
7. developer who wants insight into current software architecture
Otherwise, the book is still a useful guide to help you grow as a developer if you even browse it sporadically, and unlike many programming books, it will not be obsolete in a year.