Violence used much more sparingly would be great. In those cases it just feels more real and has some actual impact.
At the very worst, be like Borderlands: when there's gore it's not automatically tons of blood jutting and limbs aren't treated as simple physics objects (this is never convincing) and instead land on the ground and stay there like the sticky fleshy mess a limb should be. Slow motion on every kill is just too much. Sometimes shooting an enemy means I want to move on directly to the next one, I just killed the guy, I know how I did it, no need to give me another camera angle.