What is he good at? He works hard, but Daniel James worked harder.
He's not slow, but he isn't fast either. He's quicker than Mahrez and Bernardo Silva, but he's not close to having the same effect on the team as those two. He isn't powerful. He has decent technique. Very one-footed.
Is the problem that he's trying to play as an out and out winger when he should be playing more like Bernardo Silva? He can't do what Nani did. He can't do what Valencia did. Ronaldo shouldn't be brought into this. He certainly can't do what Giggs did. So, we can't expect him to do what our former wingers did, nor should he try to. Trouble is, he can't do what Garnacho does, or what Rashford (when bothered) does either...
He turns very quickly and shields the ball quite well, so maybe he would be better down the center - no idea.