That sucks that it did badly. It absolutely killed in the theater when I went Saturday and Sunday nights. The whole crowd was cheering like a bunch of kids at the end of each movie, both nights.
I think the advertising for it is badly done. I had no intention of seeing this movie based on the previews, but the word of mouth from people who went Friday night convinced me to give it a chance. Everyone I know who has gone to see these movies has been blown away by them.