I would get this game but the demo ran pretty poorly on my machine even with most of the details turned down; guess it's time to upgrade the hardware first.
As with most of you, I had mixed thoughts about the demo. The plot sounds interesting, and it looks like there are strong ties with the original story. The weapons have much nicer effects than in the first game and the nonlinear gameplay and level design (i.e. multiple ways to get to various areas and to complete objectives) is all present. The graphics has all the Unreal Warfare goodness. That bloom graphical effect is very realistic, but makes most things look too blurry; good thing it can be turned off.
I actually spent nearly a hour finding out what the various characters in the demo say if you bump into them, throw objects at them and so on, since there are a
lot of things they say for such events. As in the first game, there is some unintended comedy; pushing the large wooden plank things stacked along the walls of the greasel pit onto an NPC creates some wacky physics effects, same goes for dead bodies that get stuck in doors at certain angles and one time the SSC guards and Sak inexplicably got into a free-for-all fight with each other.

Most of my gripes have to do with the "streamlining" that has resulted in oversimplification of the game mechanics. The skill system was removed altogether, the aiming feature is gone (granted, the aiming was frequently too slow in the first game, but it was a good idea in principle and works well in other games), you just have the standard single health bar instead of six different health sections and everything in the inventory seems to take up the same space. The GUI is fine but everything looks too big and is placed poorly; this really seems like console influence. For example, the transmission text comes up almost in the middle of the screen and is shown in some ridiculously big 24-point font.
From what I have heard, there also isn't nearly as much text as before; the newspapers, emails, datacubes and so on were an excellent touch in the first game, and I spent a lot of time reading that stuff. Hardly any blood effects too, which seems rather unrealistic. I don't really mind the unified ammo, though (although it makes no sense from a realism perspective); in these games, I always tend to use only the weapons for which I have found more ammo than I can carry anyway.
Still definitely worth getting for me (once I get a better processor and video card), but it isn't up to the standards of the original.