Personally, I take cinema mainly as entertainment. Yeah, you can send messages, use it for politics, religion, whatever you like, because it's art. But I, as a viewer, watch movies to get entertained. After experiencing Welles' masterpiece I can say without a doubt that I was never that bored before. I felt like cutting myself just to ease the pain of that movie. Even talking about the man itself puts me to sleep.
Yeah, it has camera angles and storytelling and stuff, but I'm no movie director nor a student of that particular art, I just want to get entertained or emotionally moved, and that film did neither. Well, it made me angry, I guess that counts as an emotion?
tl;dr: the guy is boring and I can't stand that.
For me, this is his greatest accomplishment: