I don't remember the first book I read on Extreme Programming, but I clearly remember two sensations: enthusiasm and confusion. Indeed, I felt there was something great in it, but I was unable to grasp many of the real practices they were talking about; it was like I was looking at them through a thick fog; user stories was one of those practices.
Many years have passed from that day, five, maybe more; my understanding of user stories expanded from a shape in the fog to a paper card. However, as many things you learn on the Net, some parts of the card were very clear, while other were still difficult to discern: for example I was not sure how big the card should have been or how many details I should have put on it. Less confusion and a little more enthusiasm.
Then my twin brother brought me this book, and told me "read it". And as I always do with everything he gives me to read, I put in on the shelf, and I forgot it. You may wonder why I do it; you're welcome: I wonder too.
Anyway, the book remained on the shelf for many months, then, I don't remember why, I took it again and started reading it; I've stopped and started many times, then, yesterday, thanks to a trip in train, I finished it.
Indeed, Mike Cohn did a very good job at explaining user stories; many of the questions I had about user stories found their answers here, and I think I'm better at using them, now; at least, Mike gave me all the tools I needed to improve, and not only in the user stories, but in the release and iteration planning as well, two practices intertwined with the former. There was even a nice example which gave me more insights on all the process.
As a matter of fact, I don't like how the book is written: each chapter is divided in an introduction, a core, a general summary, a summary of developer responsibilities, a summary of customer responsibilities, and some questions; this structure makes hard to read the book from the start to the end, as I like to do.
Nonetheless, I like when Mike tells us not what we should do, but what he did, and this happens most of time; he shows us real life examples, tells short and long anecdotes to explain and expand what he said just a paragraph before; in short, he does what is often forgotten: he shows as the theory of user stories becomes the practice of user stories. And I thank him for this.