Bought a copy of Making It All Work at my local Border's yesterday; they had 4 copies.
I'm about halfway through. If you've seen interviews with David Allen, you've seen him chat about how the various elements of GTD work together. This book is like having him sit down with you and chat like that for about 4 hours about every aspect of GTD.
In one sense, there's nothing new here about the "system" of GTD. No new workflow steps or a 60,000-foot level, though he does rename "Review" to the deeper term "Reflect." However, he dives into much greater detail than in other books about everything; why we need to capture separately from processing, the importance of the Weekly Review, etc.
There are several deeper revelations, such as the idea that being organized means everything in its most effective place for you. This means that someone with a heavyweight, hard-to-update-and-access system is just as disorganized as someone with paperwork scattered all over the house.
Many of the questions we receive on this forum are from folks who read Getting Things Done and appreciate it, but don't understand why it works, and what each element does for them. That confusion creates internal resistance to using the system. Making It All Work will answer many of those questions.
Usually things remain disorganized when people don't confront their meaning. To actually decide what you're going to do with or about something demands that you deal with how you relate to its content, your agreement about it, and how it fits into the rest of your world.