I've just completed the demo and I have thoroughly enjoyed it. I don't see the point of me making too much in the way of criticisms here and there as this is still in development, so I'll focus more on what I liked in particular:
* Quite atmospheric (nice background low-key ambient audio)
* Rather good combat! It didn't seem just one dimensional and although I'm not bothered about bullet-time one way or another, I thought it lends itself well here. The way the sometimes enemies drop to the ground was also good for the most part.
I also liked the hit detection on the enemies as they did seem to react depending on where you hit them.
* Great level design and my kind of art/design style. The use of colour in some areas was great e.g. the blue corridor.
* Nice models of the enemies and weapons (especially the double barrelled shotgun).
If I was to hope for one or two changes to suit my personal tastes, then that would be for a quicksave function and flexibility to map your own keys, but I'm sure you're already aware of that. ;)
Also, the attack reach of the more dangerous enemies seemed a bit unfair but, as said, all a work in progress, and I don't want to niggle too much.
Btw, what did you use anything else to create this aside from Unity? I take it you need plenty of coding knowledge to make something like this?
Great work - I will be following this as it's got very good potential. I think this was the most enjoyable gaming experience I've had in a while! I look forward to seeing how it progresses! :)