Despite his cocky attitude, and his constant diving antics. There is no doubt that he's a top quality player and one of the best in his position, even at this age. He's a model professional in terms of keeping himself fit, his work rate on the field, etc. IMO there is no doubt that he provides an upgrade in quality, at least in the short term. In fact, I cannot think of a rightback that's better than him at the moment other than Lahm.
I also think it's a myth that he's not a good defender, very few fullbacks are good defenders in general, what is important is their positioning, so as not to ruin the offside trap, be able to maintain a high line, etc, and his one on one defending. He's decent at the former, and extremely good at the latter. Playing as a fullback in Barca's system is not always easy IMO. The fullbacks are required to play high up the pitch as they're the ones responsible for providing the width. At the same time, they're expected to help pressure the ball as soon as it's lost and to defend their flank.
The fact some are arguing that he might not be an upgrade over Licht absolutely baffles me.