My impressions thus far:
1) The time allotted for answers does not allow either candidate to provide a fully detailed response to, well, anything. They just go back and forth quoting the same sound bites that you might hear on a commercial. As such, this is hardly useful for gaining any sort of insight as to where the candidates stand on the issues and whether or not such a stance is warranted.
2) In this age of information, the national debate commission (or whoever organizes these things) should come up with some way to fact-check what each candidate is saying in real time. I find that this would be extremely helpful during the times when both candidates start quoting "facts" to back up their claims.
3) Along those lines, there is way too much "he said/she said" focus in this debate. Maybe it's because Palin has been the subject of a lot of soundbyte attacks herself, but she keeps trying to attack one-liners that Biden or Obama may or may not have said sometime in the past which may or may not be out of context. Then the debate degrades into an argument over what the person may have said in the past rather than actual policy.
Overall, I don't find the debate very informative, and really can't declare a winner since very few answers lack any sort of real substance. Biden comes off as extremely arrogant and dismissing when he smiles/laughs at some of Palin's statements, and Palin comes off as too, as some have already put it, "folksy."