I think he is massively overrated. He is really good but he hasn't shown anything to suggest he is actually worth the level of hype he is getting. His best game was against Dortmund, many of his best games were before teams became aware of his quality and was often given the freedom to play. Once teams became aware of this (especially that he needs to turn to play) or Monaco adapted their tactics so he had to do a job and couldn't just float about he wasn't anywhere near as good.
When you look at the teams that he is linked with Real, Barca, PSG, City, Arsenal and Liverpool he isn't going to be given the freedom he gets at Monaco unless there is a big change in their play style and is against teams that will happily just knock him every time he goes for a ball or man mark him all game (PSG being the exception).
Very much reminds me of young players that have a great WC or Euro, become hyped and make a move to a big money club but they can't do what is asked of them when they get there.