While I enjoyed the author's clear writing style, and I was pleased to see that the level of detail and explanation given in each chapter is consistent, I did not find the book's content to be particularly valuable.
The book is organized very well, and it reads like a Google Maps tutorial, rather than a hacks book. The flow from chapter to chapter is similar to the Maps API online documentation, which makes following along with Google's documentation a breeze while reading the book.
The first 100 pages were introductory, describing Google Local, the Maps API, ways to store and share information, and so on in very general terms. This puts all users on equal footing, but it seemed odd to see so much basic information in a book about hacking Google Maps.
One thing that shocked me, especially given the approach taken in the first 100 pages, was to see all of the examples written in Perl. If the introductory lessons are needed by anyone, chances are that programming / scripting is new to him/her, and I don't see Perl as the appropriate language to learn at that point.
Version 1 of the API is used throughout the book, but version 2 was released in April 2006. Version 2 is largely backwards compatible, but Google has asked everyone to move to version 2, saying that v1 support can be turned off at any point. This doesn't take away from the value of the lessons, but it does add some overhead. I consulted Google's documentation and adjusted all of the books examples for the api changes as I read.
Another thing that particularly surprised me was the mention of using scraping techniques to extract geocoding data, without mentioning the drawbacks to doing so. Personally, I avoid scraping like the plague. There's no better way to break an app than to scrape its data. Geocoding is part of the v2 api, btw.
To summarize, the book is a clearly laid out introduction to using the Google Maps API, and it is written well, but I wouldn't recommend it to a friend. For an introduction to maps, I would consult Google's much-improved online documentation, and O'Reilly's "Google Maps Hacks" is a better read for what I would consider hacks (also written to api v1).
