The examples themselves are fascinating - evolution of anti-freeze protein in Artic and Antarctic fishes, color vision through duplication of Opsin genes in birds and primates, sickle cell anemia and resistance to malaria, eye development (an creationist favorite) to skin color in humans. In each case, Carroll explains the genetic changes that the DNA has undergone over the course of time to result in the developmental changes we see.
He has also explained how inaccurate is the creationist insistence that probability of mutations resulting in evolution is next to impossible. He uses very elementary mathematics to explain how advantageous mutations can spread through a population.
Carroll has also tackled head on the problem the US schools are facing now -the disingenuous ID believers who want to teach "creationist science" (which is an oxymoron). Using the Lysenko fiasco as an example, he has clearly illustrated what can happen if there is a deliberate ignorance of evidence.
Unlike Zimmer, reading Carroll does require some basic understanding of biology (high school level at least) but he is an adept writer and worth reading. It is a book aimed at curious people who would like to know more about Evolution and the evidence we have for it. I don't think Creationists or the IDiots are going to change their minds but I hope books like this one convince the fringe dwellers that Evolution is more than a "just" a theory. There are numerous examples of evidences - from geology to now molecular biology- to show how evolution has occurred. As Lewis Black said "We have Fossils. We win."