You are a senior programmer or a practicing application architect, using, on a regular basis, the .NET Framework and the various tools and designers that come with it.
You are a Microsoft Certified Solution Developer (MCSD) from the "classic" days of Component Object Model (COM) programming and have taken at least some time to learn how .NET differs from Visual Basic 6.0 or Visual C++ 6.0.
You don't meet either of the preceding criteria, but you consider yourself a sharp person when it comes to software design, are willing to plop down the exam fee on the chance you will pass, and just want to improve your odds.
This book is not for you if
You are just getting started in programming and have little experience in high-level design of tiered applications.
You think you can learn all you need to know about the 70-300 exam from a book, without any previous experience in the technology being tested.
You are a skilled programmer, but have no interest in being an architect. Microsoft has created a new certification level, the Microsoft Certified Application Developer (MCAD), which might be more appropriate for your situation (http://www.microsoft.com/traincert/mcp/mcad/default.asp).