Amnesia: The Dark Descent is the first survival horror game that I have ever played. I can't really say that it's better creating an atmosphere than, say, Silent Hill because I simply have no experience when it comes to horror games, so forgive me if I say something stupid here.
I believe that the game has some nice touches, the bugs scattering the floor, the occasional scream when you feel particularly safe, the fact that you have to find out if you have to pull or push open a door every time you're running from a monster and then crying on the floor on fetal position because you spent two seconds pulling the door instead of pushing it and you felt that two seconds was enough for the monster to come right up to you and bite your skin off but you're also too afraid to look behind and see how far it is because that would just burn even more precious life-saving time. It's a pretty scary game, at least for me, an inocent soul from the magical land of unicorns and lollipops but I'm afraid that means that what I experienced as pants-soiling horrifying might be a small scare for someone with (any) experience on horror games.