What kind of political ad works best?

We’ve seen lots of mud-slinging via commercial during this year’s presidential election. Negative ads work to some extent or they wouldn’t be used. However, this morning, I saw Barack Obama’s newest commercial. It is all  about his economic plan, and he is on camera and talking for all of it. I think it was effective–he laid out his principles and what he wants to do for the American people, and of course, he dealt with the hottest topic du jour, the economy. It made him look serious and proactive. Let’s see what McCain responds with. In a way, I think Obama is trying to look presidential to conteract McCain’s grandstanding of these past two days.