I'm liking the game, just not this demo. Let me explain...
I wish this demo had versus mode, because it is so short. Unless your playing on Expert difficulty you will beat the demo in like 15 minutes (granted, the extra time spent will be on retry's). IMO Advanced difficulty should be halfway between what it is now and Expert, because Expert is just unreasonably hard and Advanced is still too easy.
Also, control customization is extremely limited, your given four control configs and some buttons are constantly the same throughout *cough*Reload is always B*cough*. I expected, this being a Valve game, to be able to change any button to whatever you wanted.
Other than those two things this demo is awesome!
Side note: anyone have any tips for using the Hunting Rifle? I see it as a support weapon for hanging back and taking out enemies from afar. However, 3/4 of the game is extremely close quarters and since you only have one primary weapon it has to work in the majority of situations which it seems incapable of handling.