The new eastern and western guides have attractive covers featuring Peterson's artwork, similar to the 2008 Peterson and unlike the style used for Peterson guides covering other taxa. The eastern guide has a Northern Mockingbird; the western guide has a pair of American Kestrels. The books' front and back matter feature several photographs taken by Jeffrey Gordon. (He recently devoted a series of blog posts to the photographs used for the Peterson guides. It is worth checking out his posts, even if you are not interested in these field guides.) The western guide is about 50 pages longer; both guides are small enough for a jacket pocket but too large for a pants pocket. The books have associated video podcasts, available online.
The revised guides use Roger Tory Peterson's classic bird illustrations, the same as have been used in past editions of the Peterson bird guides. However, the colors appear fresher and the bird illustrations are reproduced at a larger size compared to my fourth edition of the eastern guide. Another change that I noticed compared to my older edition, is the addition of short sections on how to identify shorebirds by shape and how to age gulls. While these sections are not as good as the ones in Birds of Europe, they should help less experienced birders with those difficult groups.
Taxonomy has been updated to reflect classification and name changes through the 50th Supplement to the AOU Checklist in 2009. Because of recent taxonomic splits and observations of new species for the ABA area, Michael O'Brien painted new illustrations for the revised edition. The new illustrations follow Peterson's simplified style but have subtle differences. On O'Brien's paintings, such as the illustration for Cackling Goose, the individual brush strokes are not as noticeable as on Peterson's.
Opposite each plate of illustrations is a page with short accounts for each of the species depicted. Each species accounts contains the English and scientific names, dimensions, and notes on identification, voice, similar species, and habitat. The species accounts are written in Peterson's telegraphic style, in many cases with his exact words. However, they have been updated with additional information, especially if new identification methods have been developed by field birders.
Range maps accompany the species accounts on the pages opposite the plates. They also appear in larger form in an appendix. Range maps in the appendix include explanatory notes for each map, while the maps beside the species accounts do not. Though the range notes provide some useful information, I generally rely on the map opposite the plate when I am in the field and rarely check the map in the appendix. If other readers do the same thing, the range map appendix may just add bulk to the book. In my opinion, these maps did not need to be printed twice, and the appendix could be excised to make the book lighter and smaller for field use.
Even though over 70 years have passed since the eastern guide's first edition, the Peterson bird guides remain a worthy choice for North American birders. Whether you want to use this guide will depend on your own needs and tastes. The simplicity of Peterson's approach and clear explanations of field marks makes these excellent guides for beginners. However, intermediate and experienced birders will likely prefer more advanced guides since the Peterson guides' plates lack many plumages.