I teach XNA to undergrad game designers and have assessed almost every XNA book on the market since XNA 1.0. I will shortly be adopting this book for use in the classroom because this is the best XNA book I've seen yet. It covers the basics that are hit by most beginner XNA books, but goes into far greater detail on each subject, so it really takes the learner a lot farther than those books. For example, I'm a huge fan of Aaron Reed's XNA3 book from O'Reilly, but this book goes a lot farther with the same subjects.
Probably the single best feature of this book are the additional learning exercises tacked on to the end of each chapter. I actually like the fact that the answers to these extra exercises are not given, because in each case they're easy to figure out and the learner isn't tempted to just open the answer files. These extra exercises are very well thought out and nicely compliment each chapter. My only complaint is that I wish there were more of them.
Another good idea here is to take a direct, non-class-based approach to most of the code examples. In most 3D chapters, all the code is implemented in Game1.cs, with a separate Camera.cs file being the only external (allowing you to move around the object you've built). This is really helpful to learners, because examples that are separated by class have to be broken down and then rebuilt into new class arrangements to suit their own projects. Here they can focus on the code, then break it down into their own class structures right away.
The downloadable code collection is extensive and very well organized, and handily provides each sample in both Win and Xbox formats. There is an errata sheet at the author's site that seems to be actively updated. There aren't many mistakes in this book (another big plus), but I'm glad to see that they're correcting them.
Note: This book is not for beginning programmers, and has nothing about the basics of programming, such as classes, variables, data types and so forth -- it assumes you already know about the basics of OOP, which I think is appropriate. It does have a very handy intro to debugging and editing in Visual Studio (with some good tips). Rob Miles' "Learn Programming Now: XNA GameStudio 3.0" is a little better for raw beginners, and also a very good book, and a nice compliment to this one.
Recommendation: More experienced users should combine this purchase with "XNA 3.0 Game Programming Recipes" by Riemer Grootjans. That's a one-two punch that will get any new programmer a very, very long way. Less experienced users should combine this purchase with the Rob Miles book mentioned in the paragraph above, which covers much of the same territory but will give you many additional examples and other kinds of problems to work on.