It depends on how you score. 
I see three scoring scenarios: 1. Best conservative performance 2. Best electability performance 3. Best positional performance
Conservative performance is pretty clear: whose answers appeal to conservatives? (Does not mean conservatives believed the candidate meant what he said.) This is not Tea Party scoring, either. I’m not limiting my evaluation to the 3 core Tea Party principles of Constitutionally limited government, free markets, and fiscal responsibility. This is broader conservatism.
Electability performance means the candidate appealed to general election voters. This doesn’t meant centrist—it means not scaring the crap out of people who aren’t politics wonks. (That’s most voters, by the way.)
Positional performance means the candidate did what what he had to do based one his current standings in he nomination process.
On conservative performance, I have to go with: 1. Santorum 2. Perry 3. Gingrich / Romney
Electability 1. Santorum 2. Gingrich 3. Romney
Positional 1. Romney 2. Santorum 3. Gingrich
If we give 3 points for first place, 2 for second, and 1 for third, we get this composite ranking: 1. Santorum: 8 points 2. Gingrich: 6 points 3. Romney: 5 points
What does it all mean?
Santorum should move up a bit in the polls before the New Hampshire primary, but not enough to win. He needed Romney to finish out of the top 3 in this debate.
Gingrich needed to pull Romney out of the top 3 and get closer to Santorum than he did. This hurt Newt.
Romney improved his chances, but he didn’t close the deal. The longer he lets Santorum and Gingrich stay in the game, the more vulnerable his lead becomes.