I haven't read this book from cover to cover, but here are my impressions anyway: this is quite a comprehensive coverage of the subject, looking not only at the Lotus 78 and 79 (from 1977-1979 seasons), but also at the cars that came before, including (briefly) the March 701, and the 79's successor, the Lotus Type 80.
There are plenty of photos, not only from the races, but also from the workshop with the cars under construction. Many of the pictures are ideal reference for modellers, with lots of bodywork removed. Be advised, though, some of the detail pictures are of the prototype 79, which differs from the ones actually raced (and modelled in 1/20 scale by Tamiya and Hasegawa).
If you're interested in Lotus, or F1 history, or in modelling these ground-effect John Player Specials, then I would definitely recommend this book.