I find it impossible to sneak up to guards. I'm sneaking in some place and I ofcourse I think I can sneak up on a guard and finally use my knife for something.
No matter what the guards seem to be alertet by my footsteps when I get very close.
Otherwise the sneak gameplay, with the field of view of the guards, and sound meter is awesome. The material is definitely here, it should just be changed so it is possible to sneak up close and stab someone. Otherwise you never get to use the knife or dragging bodies.
With some patching and or modding this game could is one of the best FPS's made.
I've managed to backstab several soldiers. I wonder if the people who are having problems are switching weapons when near their target. If you watch the noise indicator at the bottom right it spikes when switching weapons and I think reloading too. I've had not problems with a static target facing away from me at all.