The Belgian midfielder provided two assists as the Clarets defeated Watford 2-0 at Turf Moor on Monday night in what was a Man of the Match performance.
"He adds, for sure," he said of the 28-year-old.
"We worked very hard on that deal, we felt he would add some quality, he has a great manner to him, he wants to develop with the team, and he definitely adds something to the performances.
"And I think that rubs off on others, sometimes you get that person in who just has that bit of calmness and an assured manner in possession, and that rubs off on others and adds to the belief of the group.
"He has made a really good start for us."
Defour has now been involved in four of Burnley's five Premier League goals, scoring one and providing three assists.