I'm not even a big fan of Supes, but dude deserves better. A Superman movie should be about as dark as "Spider-Man 2," maybe less. The film could increase the action without being a near rated-R frown fest. And last time I checked, "Iron Man" made a damn nice chunk of change last summer, and it was mostly shits and giggles.
Some characters like Batman, the Punisher, or Wolverine are suited for dark stories. The movies tend to go awry by having the heroes kill or let the villain die. I understand the general movie audience is used to seeing the bad guys get theirs after 2 hours, but there is a line. Batman tying a bolo around the Joker's leg to a stone gargoyle - wrong. Daredevil letting the rapist who beat him in court get run over by a subway train - wronger. Bats leaving R'as Al Ghul on a runaway train - wrongest. There are other ways to tie up the story without having the villain die, or at least have them die from something of their own doing (I don't know, getting stuck with their own bomb, for example).
Am I being too much of a stickler for the rules set by the comics' version? Maybe. But I just feel if a character/story is good enough to adapt, it's good enough to adapt right.