Much replay value: targets change location (or even identity, re: party) on replay, many alt. routes. More of this pls.
This is part of Dishonored's huge potential as a replayable game, but there's more to it than just your chosen approach and the game's endings. The mechanical design encompasses some quite major changes for returning visitors. You will not simply follow your footsteps to find every target, because in some cases they will have moved to different locations. In a mission where you must uncover a target's identity from one of three masked siblings, it will not be the same sister again. The survival, or death, of a character can open or close another of the story's branching paths. Compare notes with a friend, and you'll realise that you had significantly different experiences of Dunwall.
A lot of stealth games have tried to promote a "play it your way" mass appeal, but it's rare that it works out to everyone's satisfaction. That said, nothing can help the kind of bonehead FPS fan who a) plays as quickly as possible and b) knocks two hours off their real completion time and brays for the internet's attention about how "THIS 6 HR GAME SUX, NOT WORTH $60/£30", etc. Yes, you can blaze through this if you have no interest in the years of work and love bound up in it, but if you *only* play it that way and only play it once then you have only yourself to blame.