I still never understand why people would play a game like this through again, you already know all the 'levels' the missions and story. It would be a chore to me.
Oh and bets are on for how many weeks until we see DLC?
Usually i would agree with you, but games like this, splinter cell, metal gear solid (in particular) and hitman i could play over and over due to the variety of how you can do things and trying to do it without setting of an alarm or being completely non lethal, not really for the achievement but more the challenge.
A game like COD/Portal/Bioshock i would completely agree though.