Just a CP of what I said in another thread about it...
I didn't find it scary, just mostly intimidating... like stepping outside of that sphere for the first time. There were a couple of other bits as well, such as this bit where you were a sort of small doctors/morgue room, and you're wading through the water and can see the silouhette of a splicer, then the lights go out and he's gone.
Another bit near where you just get the shotgun for the first time lying on the floor. There's a room there that is like a doctors area. There is a dead splicer lying on the table. You walk in and there is a tonic on the desk. You go up to it and the room fills with steam. You grab it and turn around and there is a splicer like, 2 inches from your face staring at you.
The "worst" bit (i.e. the bit that freaked me out the most) was the bit on the Cohen levels where you go into this room and there are 3 or 4 "plastered" splicers on each side of you bowing down. You run through and go into this room where you have to press a button to get into. When you come out they are all gone and you can now go into the basement. Going down there, there is water on the floor and a tonic in the far corner and nothing else. You run over to it and turn around and all of the splicers that were in the other room and now behind you doing a pose but not moving.
Oh and one other bit on Cohen's level. You in this room and there is a safe in the corner but also a flickering white light, and in the corner is a plastered splicer who is facing the corner sitting on a seat. Just gave me visions of Blair Witch Project. Was even worse when I opened the safe and the splicer had moved to a couple of inches behind me... nearly pap'd
Overall though I never found it scary, but I did find a lot of the bits really intimidating and you ended up having to force yourself to go into a few places. But I like how they never overdid it, there was about 10 places like this in the whole game for me and that was enough... it never tried to do a doom and have a splicer jump out of every corner like "BOO!" like Doom did with Imps.