That's a pretty good book. It picks good personalities to profile and writes those profiles well. The only real difficulty I have with it is that by presenting church history in ABC fashion the sense of a timeline and the context of their lives is lost. Calvin (C) comes before Hippolytus (H), and so on.
As books go, I'm a fan of the History Lives series. Each of my kids read straight through them at about age 8. For somewhat older kids, Reformation Heroes is a wonderful book, beautifully published, dealing directly with the Reformation. My son loves it, and even I learned much from it. But some of the stories are a bit rough for younger kids, telling of such things as heroes burned at the stake.
Your question makes me wonder about Reformation themed curricula for kids. There must be some good home school stuff, but for the life of me I can't think of anything in the Sunday School lesson vein. Hmmm. Maybe I should write something...
PCA, worshiping with some fine Baptists in Colorado