Jennings begins with a short history of cartophilia, using his younger self as a case study but reaching far back into history to explain many peoples' love for and attraction to maps and the information they record. He talks to educators about geographical ignorance and its prevalence today (and about how over-reliance on GPS navigation isn't helping matters any in that department), and visits the Geography and Map Division at the Library of Congress. He profiles collectors, dealers, and thieves, meets hyper-travellers who try to visit every country on each (or the highest point in every state, or every Starbucks location ...), and dreamers who spend decades creating fictional worlds and everything that comes with them.
In a particularly timely section given the recent kerfuffle over Rick Perry's hunting camp, Jennings provides a litany of odd or outdated place names, pronuciations, and long-running cartographic errors, and visits the National Geography Bee. He meets the founders of geocaching (and tries out the activity for himself), and the engineers at Google who built and maintain Google Earth. It's quite a bit to pack into 250 pages, but Jennings manages to do it extremely well; he covers a great deal of ground, but does so thoroughly (and there are notes in the back if you want more detail, plus some very entertaining explanatory footnotes).
Jennings' sense of humor is a bit on the corny side, and he likes to throw in laugh lines at every possible opportunity; most of these rated a smile or a chuckle, but I definitely cracked up more than a few times, too. Oh, and you may find that you want a good atlas (or at least Google Maps) nearby while you read - there were several points where I just had to see what he was explaining.
Whether you're a "maphead" or not, I have no doubt that you'd both learn from and get a kick out of this book; I know I did.