Let me put this in perspective for some people who are disappointed. I mean first off I mentioned a few times before that this would happen because of WWZ and MU, but whatever.
Superman Returns had a budget of $270mil, and it made $200mil domestically over the course of it's entire run.
Man of Steel had a budget of $225mil, and it's practically locked in to hit the $200mil mark by the end of the weekend.
So while a 70% drop is disappointing, it was kinda expected given the circumstances, but you need to look at the bigger picture here. We also don't know what the OS box office is yet. MoS just opened in some countries today and some countries have to wait even longer. It's safe to say MoS is gonna be fine.