President Bush was, again, on the defensive from the outset. He spent so much time portraying Kerry as a "Massachusetts liberal" or taking cheap shots, he rarely answered a question directly. When stuck, Bush resorted to sweeping ideological generalizations, in effect saying freedom and tax cuts would solve all of America's problems. When really stuck, he resorted to bad jokes.
By contrast, Kerry was in command of nearly every subject. He was especially strong on the expired assault weapons ban, the minimum wage and homeland security. My only significant criticism is that Kerry rarely explained the details of "my plan," but that's somewhat understandable given the limited time format.
The bottom line is that Kerry not only sounded more presidential, but looked presidential. By this measure, he was the clear winner.