Now as to the actual subject, the authors DO cover it well. Java and C# are like Spanish and Portuguese. If you know one and not the other, it will still be recognisable. The structure of class files and the syntax are broadly the same. Certainly, you won't have any difficulty with the concepts.

A key difference though is the ability to use pointers. Java does not permit this in its standard formulation. (Though through JNI you can effectively manipulate pointers.) C# lets you use pointers through its "unsafe" keyword. The book only devotes 2 pages to this. Very cursory. It points out that bugs in pointer arithmetic are responsible for a lot of C and C++ breakages, and pointer manipulation is often exploited by worms and viruses. Given the ongoing propagation of these on Microsoft platforms, and that .NET/C# is run on those platforms, and that Bill Gates himself says Microsoft is putting more emphasis on fighting them, a more extensive explanation would have been merited for the benefit of non-Microsoft developers. Related to this is an explanation of when it is ok to use pointers (Eg. for higher performance if you have special hardware.) But there is no treatment of this at all. Pity.