I came away with much the same feeling about GH as you did Min. He seemed to readily accept the viewpoints of other researchers, past and present, such as Posnansky, Hapgood, West, Bauval, et al. Whether he meant to come across that way I'm not sure. But in doing so, he didn't seem to come across with his own position very well.
That position to me seems to one of Hyperdiffusionism, meaning that there must have been a higher civilization in humanities past and it had been lost, rather than the smooth linear growth to civilization that we are taught today.
Nothing else he said made more sense to me than the fact that at the end of the last glaciation, enough prime real estate was submerged as to equal the size of a continent. With the melting ice and subsequent rise in sea level, also came dramatic climate change. Steppes became forests, and lush savannah became arid desert. This created a human diaspora larger than any before or since. With that diaspora went bits of former culture, language, and knowledge. I personally believed this before I read this book.
More than reading this book however, the real education I got was experiencing the reactions of some people to the review, and their overt attempts to silence it. Before that I didn't realize such primitive attitudes still existed, even though history is full of the tragedies of Spanish monks and Nazi book burnings, so perhaps I shouldn't have been too surprised.
All in all, to the novice who is interested I recommend the book, along with a study of orthodox explanations. Too much of either side can create imbalance.
Thanks to Min for agreeing to help and act as the protagonist. That was in the beginning anyway. He didn't give it up. For myself, I had a lot of fun.