Critical Research Failure Strikes Again
So, Common Sense has given this game a Not For Kids. I feel this is inappropriate - There's no bloody on-screen violence, what is there is offscreen and not shown, there's only mild language, and little to no sexual themes.
So, that said, why did they give it a Not For Kids? Well, it's not just being a bit too far on the safe side; they have reasons.
The primary suspect, I think, is that what little sexual and alcoholic reference there is involves a group of teenagers. None are 16 or 17 to my knowledge, they're 14-15. For example, at the very beginning of the game, you see a fictional commercial for a product called Quelorie Magic. It's endorsed by a pop star named Rise Kujikawa, stage name "Risette", no older than 15, who says lines like "I'm tired of dieting and going to the gym is too hard!" and "Good thing there's something even I can handle!" The satire is very subtle. (Not.)
For another example, if you date one of the girls in-game, you'll get a scene wherein it's heavily implied they and the player have sex. Related, it's entirely possible to cheat on the girls and date all of them at once, though you do get a rather scathing punishment come Valentine's Day, on which you can only spend the day with one girl.
And, most incriminatingly, one of the dungeons in the game is an exaggerated version of a Strip Club representing the aforementioned Rise's frustrations at being sexualized and marketed as a brainless ditz to the public.
That being said, all of these pale to what a 15+ year old has already heard from their peers at school.
And, hey, there's good messages, and good role models. The entire message of the game is that repressing the negative parts of yourself is unhealthy and dangerous; the heroes only gain their powers by confronting their "Shadow", the repressed parts of the psyche that they don't want to acknowledge. And this isn't a "Be yourself" thing either, these are very negative things: Your best friend feels bored with his life as it is, and his friends are holding in hidden desires to feel like a knight in shining armor, or feelings of emptiness and loneliness.
Which isn't to say they're bad people, they just have flaws, and there's nothing wrong with that. The aforementioned best friend is a responsible individual and the second-in-command of your Investigation Team. Rise is, despite mild bitterness towards the industry she used to be a part of, a very caring, positive individual.
All in all, Persona 4 isn't for your 10-year-old, not by a long shot. But it's certainly not "inappropriate for 17 and under" either. And it's a great game, so there's that. It's certainly better for kids than grim and depressing Persona 3 with its themes of death and loss, and Common Sense gave that a 16+.