Cumberbatch is very well known outside of the U.S.. I still believe his casting was inspired and had vast potential, even as Khan.
The problem is, the core of any movie is the writing. Remember what happened with Prometheus last year? It had huge buildup as well, but the story fell apart. Eventually, so did the grosses. The fanboys hated it because the plot was a contrivance.
FWIU, the plot here is vastly better than that of Prometheus, but only by the hair of the last dog. The Dark Knight held people not because of the Joker himself, but because of the conflict in the movie. Batman v. Joker.
People need a stake in the movie. Did the writers provide them with enough of one?
And yes, let's get more real numbers from Domestic to see what's happening over the weekend.