Honestly, I expected McCain to come in a bit tired, a bit off his game, given the events of last week, his push first to not debate and suspend his campaign, then resume and debate; the tiring work of negotiating with Republicans and Democrats in Washington over the bailout.
But he surprised me--I thought he was on his game, had good specificity in what he said, told some good stories that connected with the points he was making...and of course it helps that I agreed with him on many of the foreign policy issues up for discussion. He had a strategy, stressing that Senator Obama "doesn't understand", several times, and he executed it.
That said, I still think it was more or less a draw; Senator Obama is a good debater, too, and is learned on several issues. Which will make the debates coming up even more important.