To me, Feingold came out ahead.
I had little background coming in; I kind of know about Feingold. As far as senators go, he seems okay in that I don't know of anything especially bad he's done. I do know he was the only dissension vote against the Patriot Act in the senate!
Johnson on the other hand, he seems like someone grabbed a local business man/owner? and put him on stage. Also his daughter was in the hospital a lot and he's carried a pocket Constitution for a really long time. He smells like Tea.
They didn't talk much at all about their visions, but at least Feingold brought up alternative technologies and recognized Wisconsin's unique involvement with stem cells. I was pleasantly surprised to hear Feingold's position in support of the second amendment.
Otherwise, I think it was a pretty straightforward debate and nothing out of the expected. If someone is going to beat Feingold, Wisconsin can do better than the other guy.