It is an interesting book.
It is NOT a sensationalist book (despite the stupid illustration provided by the publisher to the press) the author is a qualified and practising archaeologist who has made a case for the theory that much of Britain at the time Stonehenge was built was covered in water (as a result of the impact of the Ice Age) he makes a reasonable case for this based on post hole evidence, plus other evidence found -and ignored or just not understood, in the main- by some archaeologists.
He believes that the people of the Stone Age were not the 'ignorant savages' as depicting in some history books, that they had reasonably high level of civilisation. (For which he has some evidence.) And that they were more mobile -by using boats- than might have been thought possible.
To anyone who wonders how it could be that a civilisation's influence could be so totally lost, he points out that within 200 years of the Romans leaving Britain, all of their building knowledge, etc., was lost and that it took a very long time for Britain to regain some of what Rome had. Central heating, for one thing.
There is evidence that they practised medicine and that an early use of part of Stonehenge was for medical treatments. He provides some evidence for this.
He also makes reference to Doggerland and points out that far from the tiny land bridge that some academics still seem to believe in, Britain was once part of mainland Europe, connected by the large landmass now called Doggerland. http://en.wikipedia.org/wiki/Doggerland
It is an interesting book and worth buying. Even though the author should have employed someone to polish the text a little!