The book contains an introduction and a large number of plates with brief discussions of each. Callen is known for her interest in formal analysis, of technique, and so the book is free of the jargon (adjectives and generalities) that often mars books of this sort. The analysis is informed, original (that is, based on her own eye and examination), and takes into account much secondary literature on Courbet.
On the other hand, not everything she says is always interesting and Courbet himself is not an artist of the first rank -- even taking into account that he is primarily a transitional figure.
The prints are nearly all black and white. This is not a problem nowadays, since nearly every reader will have an internet connection at hand. But it means that the book cannot be bought for its reproductions; one should get it only if interested in Callen's text/analyses.