In short, the game is awesome, but if you want to purchase for a child under the age of approximately eleven, make a decision over whether they'll be able to handle the drinking, drugs, and violence in the game.
In depth about the game, I feel as if overall, this game is great and totally worth your time and money. The replay value is high, the story is entertaining, and this is just a generally light hearted version of Grand Theft Auto, though it isn't a GTA clone. The missions are usually short, so you can take periodical breaks without having to repeat long, drawn-out missions.
On the rating is has for kid-friendliness, it is kind of like "meh", considering the large variety of cursing, the references to drinking and smoking, and the fact that you can kill people with a chainsaw (that is, of course, only one of the ways you can kill people in this game, but that's not the point.) Myself, being eleven, has played this for about the past year, and I haven't really found anything extraordinarily inappropriate, but I would still recommend thinking about the content of this game before buying it. I hope you found this review helpful.