I think the film is a victim of scheduling. I don't think general audiences want a super-hero movie every two weeks. I know a lot of people who saw THOR because it was the first super-hero film in a long time however no one had anything good to say about it. They were just ready to see a super-hero movie. $500 million in the first week (international) for an adequate movie tells me there was a lot of pent up demand. I think GL could have just as easily grabbed that $500 million if it had come out first.

It's too much of a good thing. Captain America will probably come in even lower since it will be crushed by Transformers.