I find first and third person horror to be almost entirely different genres. With first person, it's often very easy to not be scared just by pointing the field of vision at the ground (or anywhere away from the monster) and sprinting past everything. So to make first person horror scary, they really need to focus on making a terrifying atmosphere to make the player think it's never safe to look back up.
With third person horrors, it's all about the monsters. Since you're going to have to see the monster anyways, the only way to make the game scary is to create really, really horrific monsters (or
disgusting environments), which Silent Hill excelled at.
I'm interested in how they're going to pull off first person horror, though.