From a great comic book blog: Dave's Long Box
Superman Returns is better than Batman Returns, but not as good as Batman Begins. It's also not as good as X-Men 2, but it is better than The Fantastic Four and is about a third as good as both Superman and Superman II combined. It's no Blade, but it's twice as good as Daredevil and five times as good as Catwoman. It would take all the combined good parts of Elektra, Batman and Robin, and Teenage Mutant Ninja Turtles II: The Secret of the Ooze to equal half of Superman Returns, but Superman Returns would have to be twice as rad to equal The Incredibles or Spider-Man 2. Having said that, I'd say it was a little better than X-Men 3 and four times as good as Superman III and IV (separately.) It's no Swamp Thing, though.
I hope that clears thing up.
Read the entire review at Off-topic: The Official Dave's Longbox Review of Superman Returns - Like You Care