Let's see some positives then shall we? Even if this isn't the best possible solution on paper.
1. Leadership qualities, has captained Benfica and seen as a responsible, well behaved lad.
2. He is 186m, 6ft 2 (correct if wrong pls not sure), wins his aerial duels well. He is a great passer of the ball, not the quickest, but definitely not slow at all. Last year, several sources cited him as the best young centre back in Europe after De Ligt (closest stat comparison, passing %, duels, goals/assists, concentration etc.).
3. He most importantly, has European experience, and has been a regular for Portugal NT where he's largely done well.
He's not coming off his strongest season, but Benfica fans know he is their best player alongside Grimaldo (who we also should have been aiming for, re; left back issue). I think this is a good deal for City, he has more experience than Koundé, and offers a different profile to him, if not Koulibaly, this is an alright solution. We have Bernardo, Cancelo and other Portuguese speakers in the squad so he will settle well and adapt rather easily.
I wouldn't be over the moon with this, but I think it will work out well for what it's worth.
I've attached some screenshots of a statistical comparison.