Biden did a better job of answering the questions.
Palin didn't answer some of the questions, but did a lot of talking about the subject of the question and about other issues.
One question regarding the economy was answered by Biden. Then on Palin's turn she didn't talk about the economy - she switched the topic first to the energy issue, and then next to the environment. Even Gwen Ifill, the moderator, picked up on that switch of topics by Palin.
In my opinion Biden focused too much on what McCain does wrong, and how it's not too different from Bush. I understand this is a strategy, but it started to get old. Even Palin picked up on it calling it "looking back". I wish Biden would have focused more on what he and Obama will do better.
I think the same type of strategy hurt Kerry in '04 when he criticized Bush too much, and didn't promote his plan or solution enough. I like how Biden pointed out he hasn't heard McCain's plan.
I think it was a good debate, and I think Biden did a slightly better job.