Ok, I'm fine with you saying I cherry-picked a moment, but I think this kind of summed up the experience for me.
My take is that Obama did no better or worse than he did in the first two debates...pretty consistent. McCain went for a more feisty approach, but it struck me as pandering to his base.
In modern politics, though, image is everything. I can't believe that both candidates haven't been coached endlessly on kinesthetics and appropriating the correct posture/reaction/whatever at all times.
This was not it.
This certainly did not aid in my opinion of Senator McCain:
And, of course, a study in taking it seriously