Sadly, Obama will win the debate.
First, Obama is a Chicago-style politician and I would expect him to secure the debate questions in advance, either by threat or bribe. This is the way things are done in the Windy City.
Second, he will tell lies about obscure events which the opponent cannot challenge because he would need time to research the claim. In the Obama/McCain debate, the candidates were discussing the severe economic problems caused by the mortgage loan crisis. Obama claimed that the Republicans did nothing to prevent it, but that he had filed a lawsuit to attempt to avoid the crises. This was a blatant lie, but there was no way for McCain to disprove it at that time. In actuality, Obama did file a lawsuit but it was not to avert the problem. His lawsuit was to secure even MORE bad loans for his constituency. Unfortunately for McCain, he had no knowledge of the lawsuit Obama filed since it never made the National news. Obama lied, but I have to admit it was great strategy.
Third, the words a candidate says are not as important as his image. For those people who doubt the importance of image, I will remind everyone that in the 1960 Nixon/Kennedy debate, polls showed that those who listened to the debate on radio thought Nixon was the clear winner; however, those who watched the debate on TV thought Kennedy won handily. Political analyst at the time opined that the reason that Kennedy outscored Nixon with the TV viewers was that Kennedy appeared youthful, energetic, confident and sincere; however, Nixon, who had refused makeup, sweated profusely under the hot lights and appeared nervous, anxious and insecure. Some viewers even said he appeared to be dishonest. I think that most people would agree that Obama has charisma and Romney is somewhat lacking in this attribute. That is one hell of an advantage for Obama.
Fourth, debates are not as structured as they should be and candidates are allowed to get off subject. Obama will be told what talking points to make and he will deliver regardless of the questions asked. Not only will he deliver, but he will do so convincingly. He knows what will resonate with the viewers and he will win them over.
We shall see.