I'm not too sure about what they've been saying about the game, I haven't followed it much but I was interested because I heard it was similar to Condemned and I loved Condemned (my favorite game on the 360 so far).
They just felt really stiff and clumsy, almost like you couldn't look and move at the same time like you could only use the left OR right analog at a time and it was start jerking around if you tried to use both. Also walking around would sort of jerk, not like lag, but as if they were trying to make it feel like real footsteps and it just makes it annoying and dizzying. and of course the peak out over a corner maneuver which is pretty useless for the most part.
There were a whole lot of other problems too like button presses not registering weird collision detection, and crazy slowdown when the shooting got intense... but I would assume most of that can be attributed to it being the demo version.
I would have thought they could have just grabbed the control mechanism straight from Condemned, seeing as it played buttery smooth by comparison.