This is a very important book. Although the authors recognize that there is still awfully much tot do, their analyses and hypotheses are a big step forward in our understanding of consciousness.
It is certainly not an easy book. One should have a basic knowledge of the constitution and the working of the brain.
I, personally, would have liked more concrete examples, like those for instance in the book of C.J. Lumsden and E.O. Wilson 'Promethean Fire'.
This book doesn't explain how consciousness arises, but what it is (properties) and how it works.
Consciousness is not a thing or a property, but a process (of neural interactions).
One of the reviewers here compares consciousness to a car. But a car is a thing, not a process.
Consciousness is a private, integrated, coherent, differentiated, informative, continually changing process.
The authors make also the opportune distinction between primary (animal, unconscious) and higher-order consciousness (the ability to be conscious of being conscious).
Crucial for the authors are re-entrant interactions, degeneracy (recategorical memory), and a part of the brain 'the dynamic core' (a subset of neuronal groups responsible for consciousness).
The dynamic core provides then a rationale for distinguishing conscious processes from unconscious ones (e.g. the circuits that regulate blood pressure).
This book shows clearly that the brain is not a computer and that it doesn't work as a computer program or algorithm.
It has also very important philisophical consequences, which the authors summarize as follows: being is prior to describing, selection is prior to logic and doing is prior to understanding.
I also fully agree with the authors that Darwin's theory is the most ideologically significant scientific theory ever written.
Although this book is rather technical, it should not be missed by those interested in the real nature of the conscious process.
I should also recommend the work of V. Ramachandran 'Ghosts in the Brain', for its multiple examples of (un)conscious behaviour and its philosphical implications (the body/mind problem).