it's not so addictive to where you can't turn it off and it ruins your relationship with your GF.
It is, however, very easy to spend several hours playing without realizing it, especially when you first start out.
If you are playing on a server with a bunch of idiots, it can be VERY easy to turn it off. If you get lucky and have a good team that plays together, it can be tons of fun.
EDIT: If you get caught up in stats, then you may have a problem. First off, you will NEVER be able to compete in stats with the people who have no life and play 24 hours a day. Secondly, when I have gotten caught up in stats, I have found that i end up pissed off and don't have near as much fun.