Well, i can't comment on Eyes Wide Shut as i haven't seen the film, but i really enjoyed most of his films, including 2001.
As a craftman, he is defenatly among the top ranks (and without equal in the US among the post-Wells generation), and his repertory is defenatly very unique and diverse, unlike many directors which once they find their 'voice' they stick with it to the end of their career.
As far as the complexity of his films, they are complex under a technical point of view, sure, but beyond that i think most of them are actually rather simple. Of course, they are very intelligent for the most part, which isn't necessarely the same thing.
If you want complex, try Bergman or Tarcorvsky...