I wasn't that fussed about his signing but it is what it is and the price tag means nothing as long as he improves the squad and helps the team in achieving its goals. He's done ok so far all things considered as its taken some time for new signings to bed into the team and how pep wants them to play, it will be two different worlds from what he's been used to coming from a team where you're afforded creative license to roam around the field and another where its all about positional and tactical discipline.
But if we're being totally honest he's been below average in all of the big games so far against chelsea, psg and liverpool and still has a lot he needs to improve on his game especially when playing against the better sides. It seems all the right back has to do is show him inside and have another player covering(usually a dm) and his game is basically nullified. He will 9 times out of 10 use it and once the option is closed, plays it back to whoever is playing behind him at lb. The rare times he goes on the outside he usually produces nothing.
His biggest weakness to his game by far though is how little he offers off the ball in an attacking sense when the team is building up from the back against a settled team. He will occasionally make a run in transitions during a counter but that's it as far as any movement off the ball goes. This has in turn made him predictable to defend against for the better teams and that has stood out these past few games. I know it's not in his natural game but he's competing against a player is foden who offers as good as him on the ball(more imo) but also much more movement off the ball so needs to improve that side of his game if he's looking to maintain his spot on the left side.