This mission strikes a special cord in me, as I've always been a huge fan of horror. But either I'm too dissensitized to monsters and demons, or not many games actually do a good job at it.
Either way, I'm happy to say that this mission actually made me feel spooked or uneasy, hesitant to pick things up without looking behind me. At least for the first playthrough, this mission is nicely unpredictable.
As far as I'm concerned, you're doing something fundamentally right.
The atmosphere is also really good. It really ads to the tension, and to the sense of hostility of the whole place.
Brilliant mission. Loved it a lot. Thanks.