I thought it was pretty even...but I think that Palin caught Biden two, maybe three times...really ZINGED him once...he was silent, smiled, and said, "Uhhh...." Good job. He did not expect her to debate as well as she did.
Her delivery is such that as you listen to her speak she is so folksy that Biden was lulled into thinking she's a homespun housewife, and all of a sudden she digs in and throws a jab...nice technique.
I don't think she had enough material, though- had to keep going back to the few strong points she had on her card, but that was her JOB, so I think she did very well.
Biden did well too. He'e a likable guy, but the smile he had on his face was TOO wide most of the time- almost a grimace.
That's all well and good...