I think Obama expected a different kind of Mitt Romney and a different kind of debate...
He CLEARLY was going out of his way to try and come across as the more civil and calm and measured of the two, and I still think that was a strength of the debate...
But since no one expected Mitt Romney to be THAT energetic and THAT aggressive, it was a strength overshadowed, and thus it resulted in what was, if not outright defeat, certainly not at all a victory for him tonight.
The GOOD news (if you're an Obama fan) is that not only do we know Obama CAN turn on the passion when he wants to (he used it to great effect to win in '08, after all) but whereas Romney used up most of the barbs at his disposal tonight, Obama didn't even TOUCH his stash:
He still has the Bain fiasco, the 47% comment, Romney's image as an elitist...the fact that Obama has been (and still was tonight, according to the CNN tracker) overall relatively popular with the women vote, which didn't go nearly as strongly for Romney as the male vote tonight did...
All of that and more he has to use against him and turn up the heat, which he can now justifiably do, since Romney approached a calm, civil Obama as if wielding a verbal chainsaw, as one CNN panelist put it...
Which wasn't a bad strategy, and it won the night for him, but as he gets his facts fact-checked (CNN already busted some for both candidates) and it comes time for the second debate, with expectations RAISED for Romney this time and Obama with all his verbal ammunition still to go through...