He will be an amazing off-the-ball player, one that should not be passed to often in bad positions. Instead, he will use that off-the-ball freedom to appear in great spaces and be decisive near and in the box. He is elusive and tough to block because he just instinctively knows how to attack and exploit rifts and pockets of space in the opponent's defensive block.
For the downsides, for now, at least, the issue is he is not a penetrating winger who will take on his man and beat him with consistency. He tried several times - and that's against these terrible defenders - and was easily handled and dispossessed. He is not strong and fast enough (in terms of acceleration in the first 10 meters). Maybe that will come with time, maybe not. But until then, don't give him the ball to take on players with frequency. Not his thing. Play him on his timed runs, after he's won a better position, which he does great because of his high football IQ. His thing is to move well, circulate the ball, play quick one-touch football, create dynamic plays with his great vision (check that filthy assist to Coutinho), and finish plays with his wide arsenal of shooting techniques.