Yes. Play it.
Never played the first Far Cry.
I just beat the story in FC3 last night, there's two different endings and both are awesome. It was a riot and a very well done story. It's not every day you play a one-man-army-mass-murdering-shooter game with a soul. It was a pretty cool trip and left me with a bizarre feeling afterward I can't really describe.
Far Cry 2 was boring and buggy as hell. Never made it very far into it, may go back and try it again one day, but I doubt it, too many other games to catch up on.