I find it funny that so many people think Superman is boring or straight laced/lame. If any of you nay sayers were actually reading up on him then you would realize the character as it is now is probably one of the most interesting in comics. Some of things that come up:
Jor-El was about to take part in a coup of Krypton with Zod to save the planet but backed out at the last minute and turned Zod in/led to his capture. Zods hatred of Jor-El and his family stemed from this event.
Why were Kryptonians stuck on Krypton with only a spaceship for Kal-El? Space travel was banned by the ruling council after an accident with a space ship crashing into/destroying a Krypton moon.
Superman comes from a family of scientist, in fact generations of scientists. While he may seem like a super genius on Earth, I think I read he would be of normal intelligence back on Krypton. Despite being a "scientist's son," he's able to go toe to toe against Zod and Non (not from the movies) and still hold his own. Remember Zod is a general and has extensive combat training and ablilities.
Speaking of Non, he was a scientist on Jor-el's level, that agreed with him on Krypton's impending doom. He was conspirator with Zod in the Coup of Krypton and not only was he sentenced to the phantom zone, but they labotomized him first, making him a near mindless brute.
There so much I haven't even touched that most people are oblivous to in regards to Superman.
What I personally think about Superman is this:
His most incredible super power is doing the right thing no matter what. People call this lame or mock the character by calling him a boy scout. If you don't know already or are just fooling yourself, DOING THE RIGHT THING IS HARD!!!!!!! It's so hard that when someone does it, it makes the news. There's a commercial campaign that focuses on that.
His humility. The man is a god. Yet doesn't allow arrogance to cloud his judgement or make decisions for him. Superman knows all to well where that arrogance will lead, he lost his entire planet to arrogance.
His fear. This was actually touched upon in the Justice League Unlimited finally where he squared off against DarkSeide. There's much more to it but it's a good start. Here's the video:
http://www.youtube.com/watch?v=VoJ2Bd41zsw
Just my $.02