As many have noted, the acting is mostly horrible, but the dialog was far worse, and I can't bring myself to think the actors weren't cringing inside while filming.
By far the most annoying and destructive aspect of the script is the huge number of scenes where the plot would seem to dictate great screaming urgency but the characters waste time with blank stares or senseless pauses. Any writer who thinks those devices work to heighten suspense needs to go back to school, preferably the 5th grade. It's enough to make you root for the bad guys, er, bad things.
That said, the story was incredibly engrossing -- sufficiently so that we kept the disc running with only one pause in the whole 3 hours. I'm still not sure if that was smart or stupid. I'd like to be able to vote both 2 and 9 simultaneously.