The Killcam feature used in several first-person shooters will be in Battlefield 3, a feature that is quite controversial among gamers for quite a few reasons, usually those who are hindered by it.
If you’re not aware of what a killcam is, I’ll explain it. In FPS games, a killcam is what your enemy saw before he nailed you with that sniper rifle, and was in the original Call of Duty and Halo so it’s not an entirely new idea. In short, with a bit of common sense, it will reveal the location of the one who shot you down.
The controversy of the killcam is in how it reveals the location of a player, rendering camping far less effective than it usually is, and overall has a huge impact on the metagame. However, it also balances out because you are on the move every time you kill an enemy and the fact you can’t keep an excellent sniping position secret for long is a huge change to how most FPS are played.
Personally, I feel that killcams should be an option left up to the host of the room since some love it and some hate it. However I also hate campers and I feel that standing somewhere unreachable and shooting the life out of everything from halfway across the map takes far less skill than being among the fray itself. A major upside to killcams showing who murdered you is the ability to see who is doing things like wallhacking and texture hacking to cheat.
Still, in most FPSs you will likely see your killer as you fall to your death, without the need of a killcam.