Well, it's a preview...
...and a damn good one at that.
I thought the intro was pretty effective. The shadows, guy in the distance, etc. helped convey the bleak atmosphere pretty well.
The graphical style also complemented the work pretty well. I liked the rougher sketches of the shadow and darkness. Once again, I think it was the right choice. If there's a minor quibble here, I think one thing you could do to make it seem more real is to make the faces of all the people more dirty and unkempt. I mean, they're wearing rags for clothings, but their hair is done nicely and their faces are clean. Again, this isn't a HUGE complaint, but I think if you made their faces look like the rags they're wearing, it would only add to the environment you created.
The narration was pretty good. Nothing overbearing, but fairly well done. The voice was a good fit for the character. He was a LITTLE hard to understand at times, but again, it worked. The sound effects were pretty good as well.
...As for violence, do you really need any help? :P
Again, it's very well done. As someone suggested, you could make this into a pretty damn good game or an equally good movie. Your call.
In any case, I'm looking forward to seeing where this goes. Good luck.