Potential spoilers below. Read at your own risk.
I apologize for pimping this movie. I apologize for showing any interest. I apologize for my friend Ruby, and my wife Cathy (and my sexually confused friend Jon). They are blinded by the pretty boy looks of Brandon Routh. Once you go a bit deeper, Superman Returns is full of cliche, in-your-face metaphor that's been seen before.
Man leaves. Woman can't wait, and moves on. Man returns. Man tries to get back into woman's life. Woman is confused, and cries a lot. Done. That's the whole movie. In one scene, Lois sits in front of her laptop, ready to write an article titled "Why the world needs Superman." The article is blank, and she's having a hard time starting. As tears stream down her face, the shot cuts to the cursor, which of course is shaped like the letter "I". The world doesn't need Superman, she does (the dirty tramp!). How you gonna play Cyclops like that? That's not his son!
Throw in a little Christ-figure for good measure: "I hear them crying for a saviour every day" ... "He seems to be everywhere at once" ... "A son becomes a father, and a father becomes a son" ... Get a shot of Superman in the crucifix position as he falls. Have him stabbed in the side.
A little Greek mythology for you perhaps? The references to Prometheus, or the shot of Superman with the world on his shoulders a la Atlas? Yawn. I could keep going picking this movie apart ... too easy.
The movie may have been better if you gave Kal Penn (of Harold and Kumar fame) more lines than ... zero. Geez, why are you so serious?
A few tips for director Bryan Singer. Please don't use so much symphony music. Please don't recycle plotlines from previous Superman movies. Watch the sappiness factor. And CG Superman looks as bad as CG Spider-man. Stop overusing CG!
In closing, I have an answer for you Jon. You were looking for the 15 minutes of the movie that suffered when Singer allegedly left Superman to help Peter Jackson direct King Kong. It suffered somewhere in the beginning ... all the way to the end.