Is Superman boring?
(Although, according to this guy, Superman is stupid: http://negatron.strangersandaliens.com/ep-4-superman-is-stupid/ )
But self-promotion aside, I was talking with my buddy before The Hobbit and he said Superman is a Mary Sue. Because he's too perfect, in every way, with no weakness. Uh, no. To me, Superman represents the ideal, and I would echo Phil Jimenez's thoughts: people don't like to be reminded of their own shortcomings. But, a good Superman story is not one where he is just perfect, it's one where he has to struggle . . . tackling a moral problem and wanting to do what is right, struggling to keep his power in check, etc. Too often, he's not written that way.
My other argument about Superman: I do not blame any one writer, nor is this meant to be an indictment of any one writer -- this is a broad cultural thing -- but it's hard to write a character who believes in right and wrong when as a culture we are afraid to label something right or wrong. Superman represents justice, but in our culture justice has lost meaning and power; Superman represents truth, but in our culture truth is relative; Superman represents good, but in our culture good is either a flexible standard or an inflexible and intolerant judgment. Our culture, which is becoming a post-Christian culture is also becoming a post-Superman one.