While I fully agree with the previous reviewer as to the variable quality of some illustrations, I still give this monumental work five stars. The mere fact that we now have a book that depicts all the species within the vast area covered in a decent way deserves praise. This would hardly have been economically possible without the recourse to the illustrations from previous field guides. At any rate, the book gives the intended most welcome overview. For those areas with good regional field guides, it makes sense, of course, to concentrate on those books.
By necessity, the texts in the present book are very short; but they are informative. The range maps do not differentiate by season; there are brief infos in the text, however.