Goals from Ikechi Anya and Nathaniel Chalobah earned the high-flying Hornets, now third in the table, a 10th npower Championship away win.
Zola said: "We're really playing well away from home. I'm delighted and I have to admit to being surprised by what these players are doing. They're really performing to levels that are unexpected by me, considering that we're a young team that have just been assembled this year.
"They're making me very proud and I was delighted by this victory. It wasn't the same standard that we reached at the weekend (in a 4-0 win at Birmingham) but you can't do that all the time.
"We played some good football for large parts of the first half and deserved to be in front. But Ipswich came back strongly and we tired. We couldn't handle the ball as well as we had been, but we never gave up. We worked hard as a team and defended extremely well.
"We took our opportunities. They had opportunities and didn't take them and that was the difference."
Town boss Mick McCarthy said: "We were beaten by a very good side. They're as good as I've seen this season in this league.
"We did all right to keep it to two and worked very hard. But Watford were quality and sometimes you have to hold your hands up and admit you were beaten by the better side.
"Some people seem to have a problem doing that. I don't like it and I'm not happy that we were beaten, by they were the better side and deserved to win.
"I've got no complaints on that front whatsoever. We need another four or five wins (to avoid relegation) and I believe we've got the ability and team spirit to get them."