I don't think that's particularly low, probably fairly common in CSGO even? Most noobs wonder why they're not accurate in shooters when they flick their wrist and do a 180

Most pros probably need a swipe or two with their whole arm to 180. Generally you should move with your arm, and do the first part of aiming with it, then you get the accuracy with your hand. That's why pro gamers use such big mousemats.
Check the games to see if you can turn on raw mouse input. You can in CSGO and it's critical because it means it ignores your Windows mouse setting. As a sidenote I've been playing Metro 2033 and need to find out how to make the sensitivity lower!
These were the videos I was trying to find about high versus low DPI;
Short and sweet;
This guy reviews mice very in-depth but essentially saying the same thing (not just for CSGO);