This large (and attractively cheap!) book is instantly appealing, crying out to be flipped through. There are hundreds of photographs and drawings of animals, plants, people and places, and portraits of Darwin and his peers. There are also many text panels livening up the main read with extracts from Darwin's "Voyage Of The Beagle", and his autobiography, and the volume of his life and letters produced by his son Francis. These panels tend to form an unrelated 'sub-plot' in each chapter, adding colour, context and interest.
Darwin's text is still one of the world's most important books and I was delighted to find his prose so graceful, his tone so calmly intelligent, and his intellect so sprawlingly compendious. His book went through six editions in his lifetime, during which he tinkered with the text to answer his critics; this version wisely presents the original and uncluttered first edition text. Although I understood evolution by natural selection well enough before (Dawkins fan), I had not realised the degree of detail and care that Darwin brought to his exposition, and the amount of evidence he marshals from so many directions (embryology, geology, geography, taxonomy...). He also anticipates his critics by laying out what he regards as the problems for the theory, as well as its strength. The work will be a tad dry for some readers' tastes (I took a month over it), but it is a quiet joy.
Quammen's introduction explores Darwin's life and puts his achievement in the context of the time. Included as an appendix is Darwin's introduction to the third edition, in which he diligently credits all those writers who had approached the same theory before him (including Wallace of course). There's also a biological glossary and a substantial index.
My only concern (aside from a few typos) is that the illustrations, whilst almost all of splendid quality, only rarely bear on the main text. Instead, they more often illustrate the Beagle tales from the text panels, or show people and places important in Darwin's life. This is a curious decision, given that there's scarcely a page of Darwin's text that couldn't be enriched by direct illustration or diagrams. To give one example, page 188 discusses three species of bird and a bear; but it is illustrated by a photo of a Galapagos shark. Darwin doesn't once mention sharks in the whole book!
However, this slightly odd policy is not worth docking a star from this beautiful (bargain!) book. If you're going to read "On The Origin Of Species", I reckon this is the version you want.