It's great!That's the long and the short of it for me. It's not at all because I don't like HH BXVI. Quite the contrary. I've read a ton of his stuff, and it resonates deeply with me. I think it's awesome what he's done for the liturgy. I like him so well that I was motivated to put up http://thankyoupopebenedict.com the day he resigned. (BTW, go add your thanks if you haven't already!)
Needless to say, I'm a big fan. And maybe it's because of this that I implicitly trust his judgment in this matter.
On a more human level, I think he is setting a good precedent. As he's done with the liturgy, I wouldn't be surprised if that isn't part of his motivation--showing by doing that it is okay, maybe even good, for a pope to retire when it seems prudent to do so. Most bishops have to retire at the young age of 75. That's 8 years longer than the retirement age in the US, and more in other countries. Benedict is well beyond that.
It's not at all that old people shouldn't be in the workforce. It's more that they should have the option and, in a sense, have the luxury to rest towards the end of their lives. And while JPII showed illustrated the suffering servant to the end, illustrating the dignity of those with disabilities or are elderly, BXVI is illustrating the dignity of those who choose to retire.
So I fully support him, and I am praying for him and for the upcoming election.