I have the old east/west editions. I have not seen the new one. Also, this is written from my memory since I don't have the books here with me in Hungary.
It's excellent as a general overview of a large selection of the most famous birding spots in a very large country. It is written by real birders and gives specific information on regional endemics and lists the most interesting species a birder is likely to find at each site also includes nice compact regional driving maps to reach sites and notes about how best to bird the sites. It's very readable and provides an excellent overview of USA birding spots for general armchair use. However, for any one locale it has only a few pages. If you are staying in only one region of the USA, you will want to find more local birding spots by using the ABA guide for that state or by searching the web for a local Audubon club which may have a page of the best regional birding.
This book is best if you are planning a campaign of birding which involves flying to all the corners of the country and staying no more than a few days in each place. Also, it is great for simply dreaming about such a campaign. The writing is good and there are nice NG quality photos of the places themselves rather than just of birds. It makes the book enjoyable to read.
I have found the books useful for example when I had only one day in San Diego and the book alone led me to 2 excellent sites with driving directions, the best routes to bird at the sites and lists of interesting birds to be prepared to see. In addition, I have had long drives up and down Interstate 95 on the east coast and visited Santee, SC, Okeefenokee, GA and Savannah NWR having found the places in the book and using only the book to bird the spots.
So I recommend this book if you are travelling beyond a single state or if you just want a well-written and concise overview of USA birding spots.
It's probably the best site guide for the entire USA. The other that I own is 100 best bird...USA or something like that. It is not as good as NG, but nice. ABA also has one for birding major metro areas. It is geared for the business traveller who may want to get in some local birding. I don't like it as much as NG.
EDIT: This is the prior edition I am talking about, along with its western part, in case there is any confusion. These are the previous editions of the book you are asking about despite the new title.
http://www.amazon.com/National-Geog...ef=sr_1_2/002-8908441-3811249?ie=UTF8&s=books