The first chapter of this book is the single best explanation I have ever seen explaining the distinction between Shias and Sunnis. Nasr has performed a valuable service in writing this book. Most explanations reduce the Shia/Sunni distinction to a mere theological point, rendering both sides foolish in the telling. Nasr explains the economic, political, and often ethnic differences that gave rise to such passionately held ideological differences. And he does so in an easy-to-read, captivating account.
Chapter 2 does a terrific job of refuting any monolithic understanding of the categories laid out in Chapter 1. Chapter 3 describes the role of Arab nationalism in fomenting organized Shia dissent (think Hezbollah). Chapter 4 describes Khomeini's success as the basis for global Shia empowerment--and organization, strategy and money. I also recommend Ch. 7, an account of current events in Iraq.
However, as at least one other reader has pointed out, Nasr’s insistence that the Shia/Sunni split is THE defining political dichotomy should be balanced by other perspectives. And I must agree with others, too, that Nasr’s portrayal of the victimized Shias is harder to sympathize with in the face of Iran, Hezbollah, etc. And yet, of course, historically, Shias certainly have been political and economic outcasts.
If you only read the first half of the book though, you may be left with the (bizarre) impression that Sunni prejudice against Shias generally, and Iranians specifically, functioned for the last 50 yrs or so as a geopolitically stabilizing force.
So you must push through to the afterword, which I can only refer to as his "American idealism" chapter, in which he insists that "democracy" and US "commitment to genuine political reform" in the region will ultimately prevail.
Given the violence of the Sunni backlash in response to Shia ascendancy, it is hard to see how ideas like "democracy" can have much effect on stabilizing the Middle East. Yet Nasr points to subtle changes within Iran as one indication that they can. It is difficult in the extreme, given the shape of the Saudi govt., to name but one example, to imagine regional "political reform" as a solution. And yet I don't suppose there is any other option.