Matic made the surprise switch to Old Trafford from Chelsea in the summer for £35 million and has since established himself as a fulcrum of Jose Mourinho’s squad.
United have stormed into second in the Premier League standings after eight games and Gerrard believes the 29-year-old is the ideal signing for the Red Devils.
“He’s one of the toughest opponents I've played against as a No.6,” the Liverpool legend told BT Sport. “He’s very leggy, he's good in the air, he competes, he always gets a toe in, he can run and match your runs.
"He's very aggressive with the ball and without the ball, he can burst past you with it and he can catch you if you manage to stride past him on the odd occasion.
“I think out of all the Manchester United players I've seen them sign over the years he's the one, as a Liverpool fan, I thought 'Oh no. I hope not,' and then it happened. I couldn’t believe it.”
Ex-United midfielder Paul Scholes agreed with the assessment.
“He's had a great start at United. He's been aggressive, he gets to the ball, he tackles. He's done well so far,” he said.
Matic has played 12 matches so far this season for the Old Trafford side and has yet to score his first goal for them.