Too many wildlife guidebooks simply display pictures of each species and identifying information. This Bradt's guide is a nice improvement over other books in that I found the text genuinely informative. The book covers birds, mammals, reptiles, and amphibians by family, with the natural history of each family or species. It goes into the evolution of certain groups and provides interesting insights into the behavior of some of the more famous animals. Indeed, the text reads more easily than most other guidebooks. My wife found herself reading this book during our long drives to different parks and enjoying it immensely.
Note: you might want another more traditional guidebook to help you identify species in the field (I liked Wildlife of East Africa (Princeton Illustrated Checklists)). The Bradt's guide had good pictures, but for some of the less popular animals it might not have enough to help with identification. In particular, Bradt's guide doesn't cover birds in the detail birders might wish (try The Birds of East Africa: Kenya, Tanzania, Uganda, Rwanda, Burundi (Princeton Field Guides) for birds). However, I think any safari would benefit by combining these books with Bradt's to really understand the wildlife you'll see on safari.