Played many of the newer FPS on PC with dedicated servers: Battlfield 3, Red Orchestra 2: Rising Storm, etc, and until I played PC FPS, I was very ignorant on how lag works. All of this games have lag compensation, and yes there are still bs deaths like running behind cover/walls (which are only caused by players with high ping).
Now watch this video (some of you have already seen it), and tell me if Black Ops 2 doesn't have amazing hit detection:
It works, its all host dependent but its the best netcode/hit detection you will see in consoles (without dedicated servers), and the better your connection the more advantage you will have (and thats how it should always be).