The main point of the book is that the rigid, non-compromising and authoritarian worldview of the Conservative side of the political spectrum has polarized the USA. The book appears to be well-referenced with empirical evidence for the views stated. The point that fear of change is a prime reason for the authoritarian worldview seems quite reasonable as well. Unfortunately, the book seems to be more descriptive than prescriptive in changing a large segment of the population to a more reasonable approach to solving problems.
This blogger thinks that the following review of the book sums up the issues presented quite well:
"Where political science has a long tradition of seeing political conflict through the lens of 'issues' debates about public policy, Hetherington and Weiler see the fundamental sorting process as instead a matter of personality. For them the new defining reality of American politics is a choice between authoritarian and non-authoritarian styles of reacting. The widely noted polarization of American politics is from their viewpoint a polarization between people, some of whom hold a worldview where issues are simple, choices black and white, and tradition a reliable guide to action, and others who prefer complexity, nuance, and change. Because these differences of worldview involve cherished symbols, they produce a party politics of deadlock."
-James A. Stimson, University of North Carolina, Chapel Hill