Actually their is as that video was likely played on the lowest difficutly settings to show off the loud way.
I have watched a few dev sessions of them playing through, you need to balance loud and stealth together, otherwise once the alarm is tripped you face too many enemies and loose health and die.
I will wait for the reviews once the game has been released, could be worth waiting a while for it to drop in price if theirs little replayability.
If you take dishonored their where challenges to not kill anyone or been seen at all.
Orange BB 5856/448