It would be fair to say that I may be the bulls-eye of 'target readers' for this book. I have both scientific training and a technical systems-engineering career; have read quite extensively about James Lovelock & Earth Systems sciences; have been known to hang out with astrobiologists... and yet am not a specialist in this field. I also take a great interest in sustainable development and renewable energy have also studied under David Mackay who these authors site heavily in their closing chapter. No surprise then, that I rate this as one of the best and most informative works on the subject as well as one of the most fulfilling reads of my year.
I read this book from cover to cover over a much longer time than it would normally take me to get through 400 pages. It would be fair to say that it's quite a demanding read as it will take you through some quite detailed descriptions within a multitude of scientific disciplines. It is also a fantastic example of the multidisciplinary synthesis of scientific domains that is gaining popularity against a backdrop of ultra-specialisation. There is very little `filler' although key concepts are revisited and expanded through the planetary history that laid out so skilfully.
The authors have expounded their critical step model of the story of life on Earth very effectively while remembering to point out where their concepts are disputed or built on less robust evidence. This is both masterful and humble work, acknowledging the state of the science and where its unknowns lie. I frequently stopped reading to mull over the ideas they put forward and absorb their perspectives; it's not a book for really casual reading.