This is just a little hint I want to give anyone thats playing this demo.
Many people do not seem to understand just how well the lock on target system works. In case you haven't realized, you have the ability to shoot the head, left arm, right arm, chest, or the legs after you lock on. After you hold the left trigger a diagram will pop up that looks like a human. Use your right analog stick and push in the direction on that diagram where you want your guy to shoot. Left for left arm, right for right arm, down for legs, up for head or dont push in any direction and he will shoot their chest. If you push down and aim for the legs they will drop instantly!!! Then you can go kick them around or shoot the body while its on the ground. They will even grab their knees sometimes. Its brilliant!!! Also as your shooting skills level up this becomes extremely accurate and very devostating.
I just figured I would post this helpful information for those that dont know.
I have had my 360 for 6 months and I have spent more time on this demo than any other demo I have played. I have played at least 20 hours worth of this demo. There is more to do in this demo than most people will ever even find out about. The only limit is your imagination.