I think his direction is alot of style and little substance. He makes good movies for sure, but I wonder how good he would be if you rob him of camera tricks and special effects. Nothing is wrong with style, but there has to be something more than fancy cinematography to a movie. Stripped of the camerawork, Requiem for a Dream would be the a pedestrian "drugs are bad" story.
He is aslo suffering from an acute case of pretension. Not surprising when you are hailed as a genius after two films. With the Fountain he tried to will a new 2001, or Anrei Rublev, or Seventh Seal into existence, he obviously failed in that regard (though the film is not as bad as some claim). I wish he would go back to the drawing board and try to create something small and unambitious, you got to create a small masterpiece like Winter Light before you can create an epic like Seventh Seal (unless you are Bergman in which case you dont).