As a Swede, I have seen him quite a lot and find him very promising as he was one of the most important players that won the U21 Euros 2015 and he is now part of the post Zlatan / Hamrén (manager) era that has started extremely well and beat France a couple of nights ago. He is good and a very promising talent, very similar to Stones but takes less risks imo. Wouldn't say that he's as technically gifted as Stones and his long range passes are not as good either.
Wouldn't worry too much about this transfer, will have quite a hard time cementing a place in the first 11 imo, at least if Smalling and Bailly plays at their best and as someone else wrote, defending hasn't really been Scum's biggest problem.
With that said, this thread should probably be in the general football forum, scum thread.