One of the things which attracts me to this author is he explains why things happen as they do, in objective terms. His work "America's Secret War" is so far the only explanation I've found of why America was attacked on 9/11, why they subsequently went to war in Afghanistan and why they later went to war in Iraq. There are many works, some good and some little better than angry rants, pointing out the obvious ethical and tactical flaws in US actions, but very few actually say why it happened and what the objectives were. This is Friedman's greatest strength and why I find his books, including this one, entertaining.
In this work he challenges your held perceptions that many of the things he predicts are too far fetched to be plausible by reminding us that the disintegration of the USSR was "too far fetched" a view in 1979, but 15 years later it was over and accepted as reality.
Whether some of his seemingly outlandish predictions will happen is matter for time but that's not necessarily the aim of the book. It is very well written work on why countries act the way they do on the world stage, bound as they are by geopolitical reality, which in turn is shaped by fundamentals such as geography, culture, mineral wealth and the like and thus what we can deduce a country might do, constrained as it is. He backs his statements with reasons and logic, and while some may regard the work as US-centric, he is not shy of some harsh statements of his fellow citizens and government.
The first part of the book establishes the actions of the world's most important players (past and present) and this was the best of the book for me. It gives a great understanding of the foundations of US (and other great world powers) foreign policy and thus, why these government act as they do. He then explains why other nations bind together to try to contain the US and thus, we have the great game.
The latter part of the book is an attempt to predict the future, based on the actions of how the US (which incidentally he describes as a barbarous country) will attempt to maintain it's position as the global power, and how other countries will either bend with this or resist, for their own rational reasons. This part will appear far fetched to many (including me I must say) but if you ignore the details a little and forget the science fiction and remember he is trying to give you the tone of the next 100 years, it's worth reading.
Taken together you have an good opinion on the tone that the next 100 years will take, in a broad sense and a good work on the framework by which geopolitics works. Very enjoyable.