President Bush was definitely better this time around. But he sounded angry, loud and on the defensive. His attempts at self-deprecating humor -- i.e. referring to "the scowl" -- fell flat because the audience was instructed not to respond. But he (mostly) used complete sentences and his attacks on Kerry were effective. He wins the comeback award.
Kerry's attacks on Bush were equally good. He's a very good debater. He certainly "won" in an academic sense. But if you were keeping score of political points, it was probably a draw.
One last observation: The overall negative tone of the evening reflected poorly on both candidates as much as it shows the closeness of the race. The first polls of swing voters should be very interesting.