The beautiful photos of lichens and mosses are the best feature of this book. Even many of the harder to identify crustose lichens are included and equally well photographed in this handsome guide. It is difficult to get a handle on lichen identification without some formal training, but this book will enable you to at least make identifications for some of the easier foliose and fruticose ones, such as parmelia or usnea, for example, and perhaps the more difficult ones too as you become more knowlegeable and experienced. The crustose lichen, rhizocarpon geographicum, for example, isn't that hard to identify from the tile-like pattern it makes on rocks and the lime-green color and black apothecia on the plant thallus.
Along with the photos, there are good descriptions and range maps showing plant distributions.
I had the opportunity to take supposedly the only full-semester lichenology class being taught that year in the entire U.S. by the late, great Harry Thiers, back in the mid-80's at San Francisco State University, a graduate botany course in which I'm proud to say I got an A. So I have some formal training in the area, and feel I can judge a good book on the subject when I see it, and this beautifully illustrated field guide is definitely worth the relatively modest price.