Some background from Wikipedia:
Extreme programming was created by Kent Beck during his work on the Chrysler Comprehensive Compensation System (C3) payroll project. Beck became the C3 project leader in March 1996 and began to refine the development methodology used in the project and wrote a book on the methodology (in October 1999, Extreme Programming Explained was published).So I took the book (it's the first edition) and I enjoyed it too, but differently. I might say that if Adventures is a road trip, Explained is a road atlas.
One of the things I liked about Explained (that it shares with Adventures) is the suggestion that only you can really decide whether XP can work in your context, and how. Also that Beck is prepared to offer you suggestions about when it might not.
But the world probably doesn't need any more reviews of this book so instead I'll note that I was a little surprised at the degree of upfront formality (which isn't to say that I don't think formality can license freedom to express yourself); sufficiently surprised that I mapped it to help navigate the rest. (And, yes, that's a map from an atlas.)