Amad is hopeful of playing again this season after undergoing ankle surgery at the beginning of the year.
"I think he's been great," said Rooney. "I tried to sign him for Derby, when I was at Derby, on loan. I thought I had him, really. I think it was the next day, he went to Rangers out of the blue.
"He has been fantastic, with the goals he's scored, creativity and work-rate. He's been a breath of fresh air and, of course, we'd like a few more players to step up.
"It's been a difficult season, there's no denying that, all season," he continued.
"But the new manager has come in and I really like him. The way he handles himself and speaks with the media, he's been really good. It's probably more about getting through this season now and, hopefully, starting to implement his style more and getting players in to move the club forward."
Rooney was speaking to manutd.com after it was confirmed he would play in Soccer Aid at Old Trafford on Sunday 15 June.