I'm (almost) 13 and I just started watching this show a bit less than about two weeks ago. I just finished season 1 and I have to say, it was AWESOME. I love it!!! I would highly recommend this show!!! However, there is a lot of swearing (okay fine, not that much, but there still is a lot, if that makes any sense lol) but not any more than, like, Back to the Future or something. And they never say the f-word or anything really bad like that. There is also a lot of violence. At first, the violence is like, literally honestly actually pretty similar to what I've seen on episodes of K.C. Undercover, but in the second episode it starts to get pretty bloody. So yeah, there actually is a lot of violence. Like, a LOT. I don't normally care about violence in movies and stuff, and blood doesn't bother me, like, at ALL, but even I had to close my eyes at some parts. But I've already seen 23 episodes and I only had to close my eyes two or three times. But if you are disturbed by blood or something and stuff like that, you should consider NOT watching this. Poltergeists, monsters, etc. do some really disturbing things to the characters in the show, like for example in episode 9 a guy's arm gets ripped up in the garbage disposal when he's fixing the sink. Also, while we're on the subject, this show gets really scary sometimes. It can pretty darn hilarious, but also terrifying. WARNING: THE FIFTH EPISODE IS REALLY SCARY!!! It scared me so bad I couldn't even take a shower!!! But I've always been known for being a wimp lol. But I'm actually really glad I started watching this, despite being scared. I'm not as easily scared anymore tbh, and would you think I'm crazy if I said it actually helped me distinguish the difference between reality and fantasy, what's real and what's not? It sounds weird, as this is a show about the supernatural (hence the title XD!) but when I tired to calm myself down after watching a scary episode, I repeated to myself that this wasn't real. And it worked!
In conclusion, this show can be disturbing to many viewers, evspecially younger ones, but I would highly recommend it for mature 12 year olds and anyone above that age who isn't deeply disturbed by what I mentioned earlier/isn't easily scared. This show is AMAZING and even helped me get over some really bad fears. Go watch it!!! It's awesome!!!!