Having had some time to reflect on the debate...
Romney did well and I did give him credit throughout the portion that I watched for hitting O'Bama. He probably hit O'Bama more than anyone else. He was smooth and polished. Not that he shouldn't have been. This is his second go round at this dog and pony show. He didn't make any huge obvious mistakes.
Cain did not improve on his performance from the last debate and I think that the reason for this was twofold. First, he is still depending on the, "I will get top experts together and we will come up with the best plan" non-answer answer to at least one of the questions...I can't remember which one. Secondly, he did not appear to have spent the intervening time between now and the last debate working very hard on his delivery or on his knowledge of the issues. A serious candidate would be working overtime to become an expert on every topic likely to be put to him. So, Cain was a bit of a disappointment. Not that he was bad, he wasn't, but that he wasn't better. I cut him a lot of slack because I expected him to be better.
Santorum, who I like on most issues, just doesn't come across as presidential. I can't put my finger on why but that is just my overall impression. I would rather see him back in congress fighting the good fight.
Pawlenty had some good moments but seems to be lacking sufficient fire. There is a lack of passion there and that will be his undoing in this part of the campaign. He can come back from this but he needs to hurry to avoid being painted that way with a broad brush.
Gingrich did surprisingly well given the recent upheaval inside his camp. I think he will drop out at some point because he won't be able to raise the money necessary to keep up. (That will probably be Cain's undoing, too.)
Paul was remarkably restrained and only had one or two of his trademark, "Koo Koo For Cocoa Puffs" moments. Need I say more?
Bachman had the most to gain from this debate since she has (nationally) less name recognition than the others (possible exception would be Santorum). I think that she did herself a lot of good tonight. I don't think that she did herself any harm. It will be interesting to see if she can build on this performance in the coming weeks.
So, bottom line is that Romney would be the winner except that he did about as well as he was expected to do. Not an outstanding performance or a breakout performance but that would be hard to pull off under any circumstances. Romney benefitted from not really being harpooned over AGW and/or RomneyCare. Bachman, in my opinion, wins by a nose because she stood out better than the rest of the field and didn't screw up. Not an outstanding performance but a competent one. I don't think she will end up getting the nomination (unless things really get weird). She could get the veep pick if she can keep up the same level of performance that she showed tonight, though.
As always, all bets are off if/when Perry gets in. Or Palin.