Once I was actually able to download it (without waiting in line for an hour) I thought the demo was OK.
I'd give it (again, it's the demo I'm talking about here) better marks if it let me change the mouse sensitivity -- I found the aiming way too "floaty" for my taste (and it was not compelling enough to send me hunting for .ini files or other ways to change settings, outside the game .exe). Gameplay-wise, It's nothing I haven't seen done better in a PC FPS.
In other words: I feel kinda like I went out of my way to get the demo, and the game has some nice touches, but I'm not gonna run to the store to grab myself a copy any time soon. I might buy it when it hits the $10-20 U.S. range though.
Edit: I forgot to mention that I didn't like that you can only 'scan' certain objects (that you then have to back-out to the menu screen to read up on). There is a lot of stuff laying around that I'm unfamiliar with; why can't I scan stuff to see what it is? This comment was edited on Jun 6, 19:12.