In games I'm used to (which granted are often the single player persuasion), when you add skill points, you get better at shooting.
In Dust 514, with the assault rifle and using a dual shock controller, it feels more like you can actually hit guys once you get your operation up to about 4 and sharp shooting to about 3. You see little shield and armour bars actually slide down.
I'm not sure I've gotten that much better at aiming with the dual shock - I'd say this comes from statistics only, not from player skill.
Granted it may be like this for many weapons. But if you go for the overall workhorse that is the assault rifle, it seems to unlock the potential to hit about here.
I guess that's why they start you off with about 500,000 skill points - so you sink it all instantly into one type of weapon.
But if you don't (and nothing stops you from doing this), you might find you pretty much hit nothing at any range.
Though if you find there's a particularly good newbie weapon (the mass driver, maybe? I haven't tried it yet), feel free to comment!