This is the first in-depth book on Extreme Programming (XP). If you are at home with the concepts of XP, but have lots of questions that you feel the XP literature doesn't answer -- this is the book for you! I myself have been into XP for little over two years, and I can't think of any questions I've had, that aren't addressed thoroughly by this book
The book is focused on introducing XP, dealing with things like how to tackle resistance from developers and managers; which XP practices should be implemented first; what factors are important in order to successfully implement XP, and so on.
The authors list six of the XP practices as "the bare essentials". Not that the other practices are unimportant, but they can wait until the first six are in place. The six are: Planning Game, Small Releases, Testing (unit testing only; acceptance testing can be addressed later), Pair Programming, Refactoring and Continuous Integration. These six practices are very thoroughly described, dealing with the how and why a practice works, how to start doing it, and so on. As for the remaining practices, they also explain why each practice can wait until the first six are in place.
I tried to read this book with a critical mindset, so I kept notes of things I thought they failed to address properly -- only to find that they returned to them later in the book, forcing me to cross out items on my list. What was left on my list were only minor details, except one item: I would have liked them to deal with the System Metaphor as exhaustively as the rest of the practices.
Just as "XP Explained" by Kent Beck and "XP Installed" by Ron Jeffries, et al, this book basically says that, well, it is good if you can come up with a metaphor, but if you can't, that's not too big a deal. In these books, the topic of the metaphor and how it relates to the concept of architecture, is given only a few pages (2.5 pages in XP Applied). This is a pity, because I feel that it is an important issue. (I suggest reading "XP Explored" by William Wake, which has two very good chapters on this.)
If you only intend to buy one book about XP, I would recommend this book over "Extreme Programming Explained: Embrace Change" by Kent Beck (which is the XP manifesto). This is not to say that "XP Explained" is a bad book, though -- I nominate that book to be one of the most important software development books, ever. But if your aim is to learn as much about XP as possible, this book is in a league of its own.
If you can afford more than one book, I would suggest starting with either "Extreme Programming Installed" by Ron Jeffries, Ann Anderson and Chet Hendrickson, or "Extreme Programming Explored" by William C. Wake. I think that one of these books is a good start, since they both are very practically oriented. After reading one of them, I think it's a good time to read "XP Explained", which very elegantly describes the philosophy behind XP. Finish off with "XP Applied" to get answers to all your questions. I bet that you'll have a very solid understanding of XP by then.
