The species accounts are fairly straightforward, with an overview page for each family of raptor (Accipiter, Buteo, Falcon, etc) and then several pages devoted to each species.
The species photos are certainly the main attraction, but the text descriptions accompanying each bird are well-done and include important identification tips which add a lot to a hawk-watcher's understanding of how to differentiate between similar species. The photos themselves are grouped by age and/or sex where appropriate, and certain species also include comparison shots of similar birds in similar flight positions.
Overall this is a very strong addition to the library of any birder who wants to increase their identification skill of a difficult group of birds. I'm not quite able to identify every dot I see in the sky just yet, but with Hawks at a Distance, I'm definitely getting better. I give Hawks at a Distance 4.5 Goldfinches out of 5.