The jury is still out on whether the “Francis effect” arises from style or substance. John Allen, the Boston Globe’s seasoned Vatican-watcher, does not offer a verdict himself, but presents a wealth of evidence from the Pope’s first 600 days in this bouncily readable, even-handed, well-researched book.Much of that evidence will be familiar: washing the feet of a woman and a Muslim at his first Holy Thursday liturgy; excommunicating an Australian theologian who argued for women’s ordination; holding a synod on family matters at which he made no secret of his deep concern about divorced people’s access to the Sacraments; and consistently making the world’s poorest people his focus. But there are several lesser-known, and salient, details offered her