If you are waiting to actually watch the clip and still reading, let me break it down a bit.

From what can be gleaned from the trailer you will be able to play the stealth game or go in guns-a-blazing through each level. Obviously there are bonuses depending on which style you choose but those will be based more on your own skill than any in game perks and such. You can read that as if you suck at the quick aiming controls that you can go slowly through getting the easy kills while avoiding security and patrols.

Also from the trailer it makes it seem like you will have to choose how brutal you wish to be while murdering humans. Simple bullet to the brain, sure. Multiple stabs to the gut after ambushing the target, you bet. All kinds of fun stuff from the sounds of it. It also doesn't seem to be based on the above choice either, but I am sure a silent shot to the head will help with stealth over a brutal stabbing. Just me though.

Before I let you go, we also have a couple shots of Agent 47 enjoying a BBQ with a bunch of scum bags. Granted he is enjoying it by lining a few more murders and the scumbag are enjoying beer and meat. Same thing right?