The bulk of the book is an interesting walk through history, examining the Romans, Chinese, Mongols, Turks, Dutch and other hyperpowers as well as lesser powers that didn't qualify as such due to countervailing nations - most notably the Third Reich and the Japanese Empire of World War 2, but also Nazi Germany's first cousin the USSR. Chua's notion that ethnic and/or religious tolerance is necessary for hyperpowers to develop is an interesting one, and at least superficially persuasive.
Her explanation of why the EU, the PRC, and India are unlikely to develop into hyperpowers is interesting. In her opinion, all three of these polities have internal problems that signal a reluctance to practice the necessary toleration; she cites anti-Moslem politics in the EU, the informal racism of the Chinese as applied in the PRC, and the revival of Hindu nationalism under the BJP in India as indicators that none of these nations are ready to step up and replace America as the sole superpower. So far so good, although the book's failure to take note of the populist uprising against the bureaucrats of Brussels is disappointing.
In the end, though, Age of Empires gets down to prescribing a means for the US to continue as the dominant force in world politics...except it doesn't. In contrast to the clearly written historical chapters that precede it, Chapter 12 is a mishmash of wishful thinking and selective blindness that makes you wonder if the same idiot who inserted the call for Scots-Irish ethnic identity politics at the end of James Webb's Born Fighting got hold of Ms. Chua's manuscript. Chua's call for rationalizing our immigration laws to something more akin to Canada's is sensible, but her suggestions that we somehow encourage more multinational corporate involvement overseas and pursue more multilateral actions overseas comes off as hastily written boilerplate scarcely worthy of a book this rich in examples of how not to do things. Chua doesn't seem to appreciate that the "unilateral" actions of the previous administration were anything but, and that the anger of workers who think their jobs have been shipped overseas is not something politicians and policy makers can safely ignore. It says volumes to me that after lengthy, detailed chapters on history, her policy prescriptions are briefly dashed off in a couple of pages before a feel-good envoi. It's terribly disappointing as well.
So, much like Born Fighting, read it for the history, but leave before the last act.