I liked this bug in as much as it talks about adding tests. But it's far too simple, almost to the point to the point of being simplistic. It barely covers Mocks, does not discuss heavily data driven tests, doesn't discuss the complexities of altering existing code, or working with a 3rd party library, working with time or thread dependent code, and doesn't talk about how test driven development may involve refactoring of not only the code, but also of the test framework itself.
I realize that this book is supposed to be an introduction, but it gives the idea that test driven development is easy and simple, which is not always the case. It would be a better book if it went into an example of where test driven development involves several steps back.