Romney and McCain both had great nights, because they both made the best cases for themselves. Romney came across as knowledgeable, articulate, less phony than usual, and he did a good job of pressing his management skills, temperment, and business background. McCain was the sober and mature leader, experienced, and knowledgable about foreign policy. Fred and Rudy both did well, but since they're less relevant in New Hampshire, they were boxed out of much of the debate.
Huckabee was the only candidate who had a bad night. Quite simply, he came off as a lightweight. I think this might be due to the fact that as the field gets narrowed down and has more time to speak, his shallowness comes across.