Shitty FOV, hand-holding progression and consolitis aside, I found the demo pretty fun. It's also decent length as far as demo's go these days.
Using the Darkness is pretty awesome at times, even though the ragdolls of the enemies seem a little feathery.
Also, I love the art style and it runs smooth as silk on my old-ish machine.
There is something a little "off" about the gunlpay, though. It's got the same lack of punch that COD4/MW/etc seem to have. The guns look and sound meaty, but they just don't have that ooomph you're looking for in a shooter.
For a good example of gun punchiness, the original FEAR is where it's at in my books.