Unfortunately, the film debuted it's lowest opening weekend box office numbers than any of the other films. (omegaunderground.com)
Enough doors have been left open to ensure a sequel, and the fact that X Men took in the 4th largest opening weekend box office take in history helps a great deal too. (mutantreviewers.wordpress.com)
First weekend box office is currently the most important measure of any big budget action picture's success. (flickfilosopher.com)