As a survival horror game from the Shinji Mikami (the dude who created Resident Evil) we were expecting The Evil Within to be a somewhat uncomfortable experience. But the ESRB rating makes it sound like basically living a nightmare.
The short summary lists the game as being rated M for 'Blood and Gore, Intense Violence, Strong Language' but there's much more detail if you delve a little deeper. This info could be considered spoilery, but only if learning that the game will have decapitations is a surprise.
From the ESRB site:
"This is a survival-horror action game in which players assume the role of a police detective investigating murders at an insane asylum. As players investigate and explore the mysterious environments, they use knives, pistols, shotguns, and explosives to kill human-like creatures and monsters. The frenetic combat is accompanied by screams of pain and realistic gunfire. Some attacks result in impalement and dismemberment/decapitation, with large blood-splatter effects; some environments also depict blood-splattered floors and mutilated bodies with exposed organs/viscera. Cutscenes also depict intense acts of violence: a flashback of children being burned alive; a character decapitated by a guillotine; a man set ablaze while bound to a chair. The words “f**k” and “sh*t” can be heard in the dialogue."
The Evil Within comes to PC, PS3, PS4, Xbox 360 and Xbox One from the 14th of October 2014.