You might enjoy the Nathaniel Hawthorne short story, Dr. Heidegger's Experiment. It deals with exactly this question, and concludes that if drinking from the Fountain of Youth makes one as stupid as one was the first time around, maybe it's better to stay old. That said, I'd go for rejuvenation no matter how stupid it made me act.

In our newly rejuvenated brains will hard-won experience and restraint dissolve in a haze of adolescent hormones? I think that some of what we call maturity is partly due to affects of age on the brain. If we erase those effects with nano, will people become impulsive and obsessive with fast cars and such? We know that body-builder's personalities can be affected by testosterone and other muscle building steroids.

I found an interesting point via the bit about folks refusing to make way for the next generation:

Francis Fukuyama warns in his new book Our Posthuman Future that young geezers will "refuse to get out of the way; not just of their children, but their grandchildren and great grandchildren."

Our spiecies advances by handing down knowledge from one generation to the next. But lots gets lost in this process. We continue to repeat history; experience is all too often the best teacher (and often much more interesting and fun). Though immortality would side step this sort of thing, there may also be disadvantages in this regard (aside from the increased education, enculturation neccessary for the offspring we do generate).

That is, though lacking the first hand knowledge, and context, that comes through experience, young bucks have a fresh perspective on the world, its problems, challenges. I wonder what affect immortatlity will have on creativity, innovation, and I wonder how we might address this sort of thing – creativity gene thearpy .