Well let's be honest, we were starving for a player like this. In terms of speed, strength and skill, I'm not sure a more attainable target existed. His strengths are absolutely ideal for us. He's a big counter attack threat. And he can receive a pass and break the midfield line. He has the strength to stay up and the endurance to keep going with the ball.
Around the box his decision making can improve. If we use him strictly as a wide player and instruct him just to find Higuain/Dybala, then maybe his efficiency takes a big step up.
I feel like this move is a bit of an overcompensation because we desperately needed a winger like this. Perhaps we turned down pursuits for more effective wingers that lacked the athleticism of Costa, for example.
I honestly don't know what to expect from him. I can't say that I'm hopeful he will break out and turn world class because I just don't see enough poise in the final third. But I think if the defensive work rate is there then ultimately this signing will be a success because anything he provides on the wing will probably be a big step up from our past efforts, like Sturaro for example.