Should I Get F.E.A.R 3?

Ok F.E.A.R 3 is looking really cool and looks like a lot of fun but i am somewhat of a story fanatic, so i was wondering should i get F.E.A.R 1 and 2 before i get 3 or just get 3? I don't really want to pay the extra money to get 1 and 2 but if the story is that detailed/great then i might as well. Also how scary would you rate each series, like from 1-3.