What makes azir so hard to play?

I have been playing league for a month or 2 and mid lane is my favorite. I played alot of the mis lane champs and so far azir is so fun and i have most play time on him. However people say azir is really difficult to play. I have noticed he isnt as basic as lets say oriana. So i think i want to main him but i want to know what makes him difficult so i can focus on that