What is the author's style in The Puritan Dilemma; the Story of John Winthrop by Edmund Sears Morgan?

Unlike many historians, Morgan does not try to hide his views on the Puritans entirely. While most of his discussion of Winthrop and the Puritans sticks to the facts, he occasionally makes criticisms. For instance, to keep themselves holy, the Puritans more or less converted their society into an enormous moral police force of which everyone was a member. It is quite clear that Morgan finds this arrangement miserable. Further, in the dispute with Anne Hutchinson, Morgan comments that Winthrop's treatment of her showed him at his worst and that Anne was clearly his intellectual superior.