Mitt Romney gave a tremendous performance tonight. On each topic, he had a numbered list of things to say, and he had (relatively, for him) specific things to say. Obama, on the other hand, had a more general approach. For example, he mentioned the Tax Policy Center study (.pdf) which shows Romney's tax promises are impossible, but he wasn't able to specifically say that the cost of the plan would be $4.8 trillion, and that part of those cuts would be paid for by something like $800 billion in increases on lower-income people. He failed to call out Romney for citing six studies which supposedly support Romney's tax math, but each of those studies made fundamentally different assumptions from Romney's statements.
Obama appeared to try to play a safe, non-combative game, giving ground to avoid a big moment. To his credit, there was not one particular moment that would be memorable. But Romney was so consistently sharper and more polished that he'll probably pick up a few days of positive press coverage. We'll see what happens with the polls.