One thing that's also quite interesting is the amount of games he's already played as a 20 year old (& 6 months). Although young we're signing quite an experienced player, which means he might not take as long to settle (it will still take some time though).
He's played 109 times, 97 of those in one of the top 2 leagues in the world.
At that age that's more games than: Mahrez, Silva, De Bruyne, Foden, Bernardo, Salah, Mane, Sane, O. Dembele, Coman and Sancho.
In fact off of the top of my head I could only find Messi, Ronaldo and Sterling who had started out on the wing and played more games (and are still playing).
Add that to us paying just over £20m and we're getting some deal.