Andrew Sullivan thinks it was close to a draw, but gives the edge to Kerry on style and substance:

But he was also evidently flailing at times. Throwing around the old "liberal" label was hackneyed and seemed a substitute for argument. His distortion of Kerry's healthcare plan didn't flirt with being mendacious; it was an outright lie. His answer on the environment sounded okay but isn't going to convince anyone. That he has to concede the complete absence of WMDs in Iraq is inevitably brutal on him and his argument about the war. The facts are simply against him, and it shows. He had absolutely no answer on his spending spree. None. If you're a one-issue voter on fiscal responsiblity, Kerry is obviously your man; and this debate rammed that point home. And then there were some simply bizarre moments. Does anyone in America ever use the term "internets"? Plural? I've never heard anyone in my life use this formulation. The mandatory malapropism: Bush promised at one point that he'd be more "facile" in future. That's going to be a hard promise to keep. After four years of defending the homeland, the president should also not be giving soundbites like "I'm worried. I'm worried about our country." Hey, Mr president. Join the gang. And then ythere was the hilarious answer on the judicial appointments. Bush won't appoint anyone who still believes in the Dredd Scott decision. That's a relief. But, to be honest, it's the kind of question a high-school president might give, not the president of the United States. Bush's biggest failure was to detail Kerry's record, rather than just describing it as "liberal". "Show, not tell" is a good rule of thumb for effective criticism. And then there was the inevitable "mistakes" question. Bush didn't answer it - except to say he wish he hadn't hired Paul O'Neill. You'd think by now he'd have some kind of answer. But he seems to think he is incapable of error. That, in fact, is an obvious part of the problem...

But here's the money quote:

The contrast between a man who can make an argument and one who can simply assert what he believes to be a truth was striking. If we have learned anything these past three years, it is that conviction is not enough. Skepticism, openness to other arguments, thinking outside the box or against a bubble mentality: all these are useful in a war leader and Bush has none of them. In some ways, Kerry seemed more experienced than Bush, which, of course, he is.