OK, so I finished DS1 on hard mode. It's decent, but suffers from pacing issues.
The first quarter is good, and the last third is good, but the bit in the middle is where it drags. Gets repetitive and feels just like a load of fetch quests (which, of course, it is). Once you get into the better set pieces, and different environments, it's much better.
I remember being creeped out by it the first time I played it (I think I got up to chapter 3 before), but this time I think I just got more frustrated. There are a lot of 'jump scares', where creatures just appear out of a vent and attack. That's great when used in moderation, but becomes kinda rote after a while. Ended up swearing at the TV not in fear, but in annoyance that necromorphs were showing up when I just wanted to get the objective done.
Like, come on! Can't you see I'm busy here?
I think it could have done with being a bit shorter, or improving the pacing in the middle, but overall it's pretty good. I'd say it would be better with a stronger horror atmosphere and more tension, but I know that from here on out the series gets more and more action packed.