The safe, polite word is that resigning was perhaps the best thing Benedict XVI ever did. Sometimes it is said with a tinge of damning with faint praise, but often it sounds sincere for reasons well articulated.
One could also argue that it returns the pope to a power-behind-the-throne status he occupied before becoming Number One. As prefect of the Doctrine of the Faith, As Cardinal Ratzinger, he exercised exceptional influence on John Paul II's reign, streaming with John Paul's tough policies on doctrine and adding hard line emphases of his own with the pope's permission. From all reports, he savored that role. He had the scholarly intellect and strict temperament that thrived under his predecessor. He spoke of wanting to retire the Vatican after John Paul's death.
Now he has decided to go -- but not very far. He will wander the shadows of the Vatican as an ever-present second guesser, a haunting presence as the "senior" pope who may or may not remain at the fringes. Even out of touch he will certainly not be out of the new pope's mind. It could be a no-lose situation for a pope who never seemed comfortable as the up front leader.
Count me among those who suspect that the barrage of criticism over various crises, including child abuse, ecumenical bad faith and women's ordination, dealt a crushing blow to Benedict's psyche, resulting in too great a burden for an old man to bear. That is in large measure meant as a tribute. Everything I've learned about him highlights qualities of sensitivity and compassion that would make him vulnerable to protest and attack. At the same time, flaws of ingrained clericalism and institutional rigidity blunted a fuller expression of those strengths.
As a result of the resignation, Benedict will remain on the scene, away from the pressure, as pope emeritus whose presence will be felt in mysterious ways. Unlike most retirees, he can be a presence to contend with.