By far the biggest surprise is just how good Romney looked. His answers were direct and corrected Obama whenever it was an incorrect statement, and he was very clear about what his priorities were with each point he made. He didn’t look pompous or arrogant like he has in many previous interviews and video clips that have floated around.
To be fair, Obama was really surprised to find that Romney had changed his stance on quite a few issues, including his tax policy and plans for health care. This seemed to throw Obama off of his game because many of the points Obama was making didn’t make sense given the changed position Romney had. One of the best sites to gain insight into the election is CNN
Another thing that helped Romney is that he did the age old trick of “promise everything” so that he seemed to be capable of giving the people everything they could ever want, without having to raise taxes. Obama seemed a little more realistic by saying he would raise taxes on the wealthy to support many of the initiatives he had planned which would be costly.