This is a major new field guide for North America, indeed a 'new generation' guide. Not since the National Geographic Guide almost 20 years ago has there been such an advance in field guides for this region. Every species is illustrated with just one or two species per page, giving several plumages and poses for each bird, and with identification features highlighted at appropriate places. Every species has a distribution map. This long-awaited title by one of America's best birders and artists is set to become a classic.
Sibley has fantastic information about every bird in this book and amazing illustrations. It's not uncommon for certain birds to have 5-6 illustrations. The only thing I genuinely dislike about this book is how it is set up vertically. There is also no defining lines between species which can make it confusing to which illustration goes to what bird if you're taking a quick glance at the book.