My Spec. Currently on a work computer:
Dual core Intel 2.6G
2G ram
Integrated Graphics card.
Ran fine. Had no problems getting it to work. Load time was very fast.
Summary.
The demo was cool. I actually played it twice, once with the lights how you requested, and once with lighting turned up so I could actually see what was going on.
I have to say, you've done an OK job with level design, and should perhaps add some more lights, because at the settings you reccomend, it's just too dark. Even with the flashlight, I still couldn't really see.
The sound was horribly compressed and a little too loud in places, but I really liked the way it was done. Dropping out of the shaft, I was waiting to get attacked and the noise did make me jump.
So. Overall (outta 10).
Graphics : 8
Sound : 7
Gameplay : 5
Lag : 4*
GUI hud etc : 4
Graphics were good. Not a great deal of stuff I hadn't seen before, but it all looked nice enough. The sounds as I previously mentioned were good.
Gameplay was lacking. I didn't know why I was in the warehouse, or what I was doing there, or what the spiders were, or why there was a giant diver. You worked well on the sound, perhaps some NPCs would be helpful, saying stuff like "we gotta get outta here" etc. or even telling you what to do.
LAg, only (as previously mentioned) right at the end. I had no trouble with the Big Daddy showing up, but he did lag like a total badman. I was right down to 3 FPS, which seems crazy considering it held steady at 32 the rest of the level.
Hud. I really bashed you on this one. The hud was horribly obtrusive, taking up most of the top left quarter of the screen. Considering I only used my weapon twice, and had no need to check my health, such a big hud seemed silly.
Anyway. It's a good start. And well done for having the balls to put this up, so that we could rip it appart. You have thought further than just creating a shooter, there were some nice little bits of required exploration, has potential.
overall: 56% (which ain't bad for a beta)