I liked the presidential debate better than this one in terms of rules and the "back and forth" that was encouraged. This seemed to fall back into the modern timed response format of the past few election cycles. The first debate was more old school and open in format. I think Jim Lehrer (sp?) was a better moderator too. Gwen may have had to overly restrict her willingness to push for more pointed answers or focus the response and counter-response a bit (as Lehrer did a number of times) because of her conflict of interest/book issue.
That said, Palin did very well. More than exceeded expectations. I only detected two or three times where I felt like she resorted rote speech delivery. A large majority of the time she was responsive to the question and Biden's points, was conversational in style, and was clearly keeping track of the debate and the points she wanted to go back to as time permitted. She held her own against the seasoned Biden and won on style and presentation in much the same way Obama did in the first debate.
On substance Biden came off as superior on details, knowledge recall, and breadth of knowledge. But he also was flat out wrong on a surprisingly large number of his "facts" (between 8 and 14 times depending on where you draw your line on fact vs opinions/characterization). I don't know if he was lying, I tend to attribute to Biden more of a pomposity and overreach for the sake of appearing more intelligent than he is, rather than overt maliciousness. Unfortunately a vast majority of viewers will never know about these incorrect "facts" and will simply have in their head he is superior on experience and knowledge, when it isn't as deserved as the impression indicates. Particularly unfair to Palin considering he was wrong in this way on a couple of his more assertive points in the debate, trying to make Palin/McCain look wrong or not up to the task.
But substance isn't only about detail and knowledge, Palin was better on exposition of principles, core values, and motivations. Also, given her being able to hold the stage against Biden and overcome all the negative expectation and pressure surrounding her leading into this debate, she proved she brings to bear a strong mind and spirit that will allow her to meet the challenges of the office she seeks and, if necessary, rise to the calls of being President should that unlikely and unfortunate event occur.
Biden didn't have to prove much in this debate, it was a referendum on Palin so much of the analysis and commentary on it has been focused on her. I have no doubt that Biden will be considered the winner of this debate on points, but I think Palin and the McCain ticket gained much more from it than Biden/Obama did. And Biden's performance may serve as yet another launching pad for new McCain ads, given the many factual inaccuracies and inconsistencies Biden left on the table.