The story details a year in the life of man who just exited his LEGO Dark Ages and is starting a family of his own. The book tries to sell in the idea that Jonathan's childhood desire to become a master model builder has been reawakened. In reading the book I didn't get that at all, just that the guy liked LEGO and wanted to write a thoughtful book about the world of adult fans.
Does the book cover every aspect of the LEGO AFOL community? No. How could it?! Even if this were an anthropology dissertation on the entire sub-culture (which it is not), everyone's experience with LEGO is both personal and unique. You've also got to leave room for a sequel if it's a hit, right?
What does the book have to offer up to the fans of LEGO minifigures and customs? Well, not much. LEGO minifig customizers get about three whole pages in the book when Bender attends a decal workshop at the 2008 Brickworld put on by Jared Burks of Fine Clonier. BrickArms and Forge are also mentioned in passing. The rest of the book looks at the fig as more of an accessory to the bricks themselves.
There several interesting facts I gleaned from these pages, but one in particular stood out: there are roughly 18 male minifigures for every 1 female figure put out. I had always suspected something along these lines, but now have a figure to put to it. Despite your time in the AFOL community your likely to learn at least one new thing.
So, the question remaining is, "Should I buy it?" Well, that depends. Obviously buying the book would send a message to the publishing community that more books of this nature have selling power. The book is also a good primer for those just coming out of their Dark Ages or for loved ones who kinda get this LEGO thing. If you've been actively reading AFOL sites and blogs for a year or two, then there's not much new news here (but there could be a tidbit or two).
My recommendation? Ask your local library to order a copy for their collection (this is what I did). This way you aren't out any money, but still get a chance to read it. This also makes it available to others in your community who may have an interest. More interest equals a bigger AFOL community to share the joy of LEGO with, and isn't that what its all about anyway?