Your reaction to this book will depend largely, I believe, on your pre-conceived attitudes regarding matters ethereal and the level of paranoia to which you are prepared to admit.
The book has obviously been extensively researched - whether or not you believe it to have been well researched is purely subjective but there is no denying that a lot of work went into gleaning the information.
The authors lay out the various elements of this 'conspiracy' - previous works by Bauval, Hancock, Temple et al relating to Egypt, ancient and modern; supposedly channelled revelations on behalf of nine alleged extra-terrestrials purporting to be no less than the original Egyptian pantheon; suspect interpretations of the 'Cydonia' region of Mars etc. They then tie-in the various elements of all of these subjects into some sort of coherent whole, citing connections - some tenuous, some not - as justification for their conspiracy theory.
Along the way, they quite rightly highlight numerous factual errors and misrepresentations made by the various players in this conspiracy that allow some of the more outlandish claims to appear to be, if not true, at least possible. Simple errors made by 'The Nine' in their various communiques, for example, that hyper-intelligent beings or gods just should not be expected to make. Also, contradictory positions taken by messrs Bauval and Hancock in their books at different times, depending upon which standpoint they were taking and what point they were trying to get across. I see nothing wrong with bringing these errors to the attention of the reader, as some reviewers seem to be suggesting, as it clearly indicates that expediency and personal agenda play a significant part in the way information is presented to us. Whether or not this constitutes a conspiracy is ultimately for the reader to decide.
If you are a devotee of Bauval, Hancock et al then this book will challenge your acceptance of what they have to say and why they have said it. I have read their books and must admit that I blithely accepted some of their 'factual data' regarding Egypt without verifying its authenticity - data that turned out to be, at best wrong and at worst, cynically misrepresented to corroborate their theories (your view of which one it is will depend upon your predisposition towards acceptance of their ideas).
Having some experience in the field, I have no doubt that various Intelligence agencies and other interested parties would be capable of hijacking populist beliefs for their own ends as stated in the book - there are any number of historical precedents to bear this out. The question is, do you accept the authors' interpretation of what those ends might be?
Throw in a Masonic connection, remote viewing, a spoon-bender and a few occultists and the stage is set for a, sometimes convoluted, journey into what is theoretically possible when unseen hands take the helm.
All in all, a thought provoking work, the central theme of which may or may not have any basis in objective reality. Perhaps time will tell. It is very easy to dismiss such grand conspiracies as unbelievable but then, people used to think the Earth was flat...