I have originally had a look at Scrum and XP From the Trenches around 2 years ago, I think. It seemed to be good, but too long, so I barely scrape the surface.
Recently, I have had a longer look into it, and there is now no doubt that it is a great document.
The thing is, there is little formalized documentation on practices actually put in place in real Scrum project. In Ken Schwaber’s books (at least in the first two — I haven’t read Entreprise Scrum yet), you’ll find case studies, personal comments and the like, but few simple, practical techniques. On the internet, you will find those practical techniques, but scattered on many blogs, mailing lists, InfoQ reports, etc.
Scrum and XP From the Trenches seems to be the only one to attempt to group many of those practices in a single document, backed by actual experience on the field.
At times, it can be frustrating (“we thought this other technique sounded good, but we didn’t give it a try”), but most of the time, advices are excellent. At the very least, they give you support to talk to your team (“hey, this thing here worked for these guys; why don’t we give it a try?”). And occasionally, you’ll learn that unintuitive pratices worked (for example, they did try colocated teams, as they were fairly happy with teams spread on several sites).