Though I may be a 15 year old, meaning I'm one of the kiddos making "excuses", I am here to make a point. Keep in mind that I am a fair person, I won't make this review one-sided.
Grand Theft Auto is rated M for good reasons. There're strip clubs, there's alcohol, and there's more than one way to get stoned in Los Santos. However, this is no different than the real world that we live in. When your kid grows to the age of around 14, they're well aware of these things in life. These things in the game are very real, and they always will be in our country. No matter how good your town is, there's no escaping vulgarity.
Let's start with violence. In Los Santos, even if you simply stare at someone, you might as well be challenging them to a Yu-Gi-Oh match after you insulted their Blue-Eyes-White-Dragon. They will try to break your jaw, and the cops will pop you in the head and arrest you. Now, here's a fact. In Los Santos, you need to survive. With corrupt cops chasing you and pedestrians trying to rip you out of your car randomly, you need to know how to defend yourself. If someone comes around and starts shooting at you, I guarantee that not even parents who are playing will just stand there. The blood levels are not extreme. In fact, compared to other games, they are at a very low level.
When it comes to sexual content, there's always a way to get out of it. You are never FORCED to go into a strip club. You can decide not to go in even if there is a mission. There are prostitutes on street corners, but the only way to pick them up is deliberately.
Swearing is a thing of life, as we all know. People are swearing in the most popular songs, people are swearing while in cars after being cut off, people are swearing around town, people are swearing in school, people are swearing EVERYWHERE.
When drugs, drinking, and smoking come into play, that is all a choice as well. There's only one mission where you get high, where you play as Trevor. Which was made more for the humor. Everybody was a clown and when you shot them you saw a nuclear explosion cloud that was colored purple.
The game itself is beautiful. The animation and style of the landscape is absolutely top, and I would never want to fly around in a military jet anywhere else.
Anyhow, I personally think that you could give this to your 13-14 year old as long as you knew that they are mature enough to handle it and won't go around getting Michael drunk and blowing crap up for no reason.
Oh, and another reason why this game is great, you can get a DLC called "I'm Not a Hipster" in which you get scarves.
FREAKING SCARVES, PEOPLE.