Nate Silver ran a post today talking about how the first debate usually helps the challenger. It's usually their final chance to put themselves and their ideas out there free of caricature from the other side. People think, "hmm, maybe he's not so bad after all." Mondale actually gained in the polls after his first debate with Reagan. But debates usually aren't the game changers they are made out to be, unless one guy just completely blows it out of the water/sucks it up.
Romney won, but not enough to shake up the race in any big way. And there's still two more debates to go, in which, historically, the incumbent comes back swinging.
Obama lost yardage every time he tried to go on offense. Straw men are harder to sell when you aren't the only one on stage.
Don't worry, Romney will have just as tough a time selling outright fabrications in the next two debates.