Stephen Jones booted 18 points but Wales boss Gatland also hailed the impact of returning British Lions Gethin Jenkins and Mike Phillips in Cardiff.
Gatland said: "It was a good performance. Italy are a hard team to break down, it took time but in the end it was a comprehensive win.
"James was very good. He is still learning when to make certain decisions at that position but he took his tries very well. He looked very dangerous. But we kept our patience and discipline. We didn't panic and we didn't force things and in the end we got the tries.
"We didn't score in the first half and we were tired at half time but we knew that they would be in a worse state than us and close to cracking. Perhaps we could have scored more tries in the last ten minutes but it was a game that we wanted to get fresh legs and get people involved at the end of the championship.
That broke up our rhythm and momentum. The fact that we were chasing the game at half time made a big difference as did the return of a couple of world-class players in Gethin Jenkins and Mike Phillips. They made a massive difference with their control and experience."
The victory meant Wales avoided collecting the wooden spoon and finished the Six Nations in fourth place.
Gatland added: "We are not hiding away from the fact we are disappointed to have finished fourth. We are frustrated and we are a better team than that.
"We let a couple of results slip by but we are not far away from being a good side. We are in good shape physically and we have developed some strength in depth. The tough thing with the Six Nations is your season is decided in five games. There is no time for you to play your way out of a blip.
"You live and die by those five games and potentially you can be a hero in one Six Nations and for whatever reason, could get the sack in the next. But we are aware of that."
Italian coach Nick Mallet remained upbeat despite the hefty loss in the Welsh capital.
And the visitors' were rewarded for their efforts when Luke McLean crossed for a late consolation try.
Mallet said: "I am not disappointed with that performance. I am proud of my players and they did fantastically well. We could have conceded five or six more tries.
"We had players dropping like flies, we lost Gonzalo Canale after two minutes and we had three injuries on the Thursday before the game. Add to that, we had taken 45 points against France so I am far from being disappointed. I'm proud of them."