I actually have no idea why it didn't make any money in America. You can't predict those things. But the studio made up for that with the international Box Office results. Plus when the DVDs and Blu Rays hit the stores, I imagine there will be a win margin for the studio, so all will be good (in time).
I won't get into any 3D discussion. You actually don't really need it in any movie. Do I still watch them? Yes, I do. But kudos to directors who stand their ground and say no to it (as does Zack Snyder). But a movie is not better or worse because of the 3D (Clash of the Titans may be an exception to that rule, because it might have been quite watchable, if not for that awful 3D conversion). This movie too, is silly family fun, that has some nice aliens, some bad aliens and a hero you can root for. If you don't take it too seriously then, you might have fun watching it
