Choices. Real life choices. The dark and compelling story of Niko Belic offers just that.
Having finished the story, I am here to testify that the use of or violence against prostitutes in the game is not required. Niko does not use drugs. Niko also advocates NOT driving while drunk and doesn't smoke.
Of course such vices pale in comparison to the fact that NB is a hired gun. I guess It would seem that violence, as far as society is concerned, is less harmful than either drugs and or sex.
GTA IV is a story. A plausible yet not so likely story of an immigrant who searches the concrete jungle of LIberty City in search of revenge. The story is filled with wit, anger, sorrow and plenty of laughs. Whether on a mission, meeting with a friend or cruising the streets, I thoroughly enjoyed the character dialog. Just as in real life, there's a surprise around every corner.
Lastly, I would have given GTA IV a ten. Except, GTA IV does not deserve a perfect score. The games controls should have undergone additional testing/tweaking prior to releasing the game. Though an improvement over San Andreas, the controls, in my opinion, feel too loose while driving and too tight while on foot. Secondly, the weak traffic AI continues to let down. Why would people driving on a two lane free way all change lanes en mass?
So, GTA IV, in my opinion, is not perfect. Having said that, it's still one of the best overall gaming experiences I've ever had.