I was surprised at how well Palin did, but I think that was mainly because she was dodging questions and falling back on her favorite talking points. I noticed at some points that the flow of her words was more of a speech than of a debate. She did show her teeth a bit, which is good for her. Palin looked very confident when on her talking points.
I thought Biden clearly came off as more experienced, and had some good one liners like the healthcare bridge to nowhere. He had a few stumbles, but he seemed to be more in the spirit of a debate. He did a good job not getting carried away on any pointless issues. He didn't touch Palin directly much, which was expected, although she did not return the favor.
It was pointed out that the moderation system was rather lax for this debate. I don't think Palin could have gotten away with as much canned material as she did had this been a more strongly moderated debate.