I just picked this game up not too long ago, and I'm just getting through the story missions now. (I'm on mission 4, the mission after you capture Versari Square.) So far it's been pretty smooth sailing. Died a few times, but then again I'm only playing it on Trooper difficulty (normal) so I wouldn't expect it to be too tough yet.
Though I did find that I had to turn the sensitivity on the controller up, as well as enable high precision mode before I was able to really hit accurately from a distance. Guess that's what I get for playing mostly Fallout 3 and Modern Warfare 2.