The United boss said: "I am delighted with the way things are going and I am especially pleased by Dimitar's progress in settling into the team. When you pay a lot of money for a player, he inevitably comes under close scrutiny.
"It happened to Juan Veron and Rio Ferdinand - and Dimitar has also suffered from the impatience of people when a new guy makes a big move.
"At Tottenham, he orchestrated most of their play. If at times he has looked a bit isolated, it was because our players needed to adjust to him as much as he has needed to learn our ways.
"But he has settled in very well and I have the feeling that we are about to see the best of Berbatov."