I have not played it. GTA is degenerate entertainment. It encourages decadence and glorifies and trivialises crime and violence.
That is American culture for you.
Edit: Yes, I did play it when I was a boy, and I did enjoy it, committing many atrocities, but I am not proud of this fact.
Edit 2: I hate it when games put you in a position where you are forced to kill civilians, non-corrupt police or non-immoral military personnel. The 'No Russian' mission from CoD:MW2 is an exception, because it was part of maintaining cover to undermine the antagonists (even if it did fail).
I pretended to shoot at them. I shot around them. The ones I did shoot were going to die anyway, because the antagonists would have shot them or did at the same time.