Lee Sin is really, really strong right now.
He´s clear is incredibly quick and healthy, he has incredible burst both early and mid game, tons of mobility, a shield that also gives you an absurd amount of life steal which allows you to do Drakes and Herald alone without struggling at all and the most op thing is that he can stack conqueror in less than 1 second.
He has 40% playrate right now followed by about 50% winrate and 30% banrate(data from Op.gg, Korea server)
I can say that Lee has been pick or ban since Pre-season started
Having this absurd playrate for a champion that is supposedly hard to play just shows how he needs nerfs.
The only weak point is that his winrate drops a little bit after 40 min of game but nowadays only 1 game in 10 get to 40 mins so he doesn´t really have weaknesses at the moment.