Pope Benedict XVI has been the most searing intellect to occupy the Chair of St Peter for at least a couple of centuries, and the vacuum he leaves will be immense. It was an enormous blessing to the Church that his pontificate coincided with the archepiscopacy of Rowan Williams: together they were theological giants in a sea of prelate pygmies.
See Cranmer: Who will be the next Pope?
Pope John Paul II was a pretty searing intellect too, but a philosopher rather than a theologian. I do agree with Cranmer's observation about the coincidence of Pope Benedict's and Archbishop Williams' reigns. Seeing them together, I sensed a certain warmth that was in part informed by their both being "professional theologians" as well as holders of ecclesiastical office. The idea of the Archbishop of Canterbury being a keynote speaker at the recent Synod of (Roman Catholic) Bishops would in other circumstances have been inconceivable; and Archbishop Williams made a significant contribution at the Synod.