I got one. I certainly enjoyed the experience. Original research is fun, and beyond that I had no responsibilities. Hard to beat that as far as jobs go.

It may not have been worthwhile in terms of career benefit (jury is still out). I don't want to be an academic, though I may follow that trajectory a few more years if the market stays bad. I may be able to spin off a research related startup, but that isn't guaranteed yet.

Regarding opportunity costs, I definitely missed out on getting into finance during the bubble.

(Incidentally, if anyone is looking for a python/c++ dev with solid quantitative skills, feel free to contact me.)