Could be nice, adding a "Watch out your back" factor to the game I guess. Ain't saying no to it, just... it's nice, not wow, that's all.
I guess it feels a bit too mob(ish) to me, while I like the adventurer kind of feeling to the game and not the "You've pissed a crime organization and now they're gonna gang and kill you" sort of thing...
I remember it in Morrowind, it was cool, so it can't hurt