I think Obama made a key error right in the beginning.
His campaign knew that McCain would come out attacking so Obama did too. That is all good and well if you want to stoop to that and not really talk about how we are going to fix the economy.
IMO, all Obama needed to do, right off the bat, was say that if you are not talking about how to solve the problem, you are part of the problem and attacking is part of the same old political problem. McCain would have been completely disarmed right at the start and every time he blamed the Dems or Obama, Obama could have again repeated it. With McCain disarmed, it would have forced him to talk about something that he admits he knows nothing about.
The only other mistake I see Obama making is that he is not calling people by their first names.
However, generally, I think Obama is holding his own in this format. Seeing as how he is ahead in the polls anywhere from 5 to 9 points, that is probably his own intention, holding his own.