Timothy Callahan has a great review of Elliot S! Maggin's Superman output over at Comic Book Resources.
Maggin was central to the development of the modern Superman, infusing the character with a new sense of morality and making him confront real-life issues in a way that's still germaine today. In many ways, Superman stories still haven't quite caught up with the best of his work.
Maggin also brought intelligence to Superman in a way that few writers have. His stories relied on many of the same cliches, like super-hero fight scenes and some convenient plot devices. But Superman arguably became more of a three-dimensional character in Maggin's stories than he had ever been before.
Take a few moments to read Tim's essay. It's certainly worth revisiting Elliot S! Maggin.