No it is not unprecedented. Pope’s have resigned as you know. I frankly find it refreshing that he steps down as he finds himself deteriorating and unable to perform at an acceptable level. He is 85 years old and not in great health.
Pope’s have resigned to alleviate such issues. What Pope Benedict is doing is something else. He, more than anyone else, is aware of the ramifications. He is putting the lives of future popes in great danger, and putting them in a terrible position in retaining independence from political pressure. I have been a great fan of the Pope, since before he was the Pope. And this action is a terrible disappointment. It’s not, “refreshing,” at all. Especially since he saw Pope John Paul II’s witness and love for the Church first hand.