the horror/the horror

It was some night in front of the idiot box. There was a preview running. Ben Affleck. Ugh, I say. Paycheck was the name. No bells ringing. Looked like a strict assembly line action flick. Directed by John Woo. Figures. Turns out (as I find out today) it's based on a Philip K Dick story. Now I'm aghast. And I don't seem to be alone. [what is the story/film all about?]