From an almost 13 year old girl
I would just like to say that I am used to blood and gore, so maybe you parents won't approve...
I watched Soul Eater when I was twelve, and I loved it. I had my doubts when I started watching the first episode, but I kept watching and I did not regret it one bit! Okay, so for the parents that really care for their children, and don't want them to be "scarred for life" or something, all I have to say is that, if you're okay with all the witches (except Medusa and Arachne) dressing like Victoria Secret models, then it's fine.
The only thing that most people worry about is the, err, "nudity" of sorts... *Slight spoiler* So, in the first episode, Soul and Maka are sent to get their final soul, a witch's soul. They "meet" their target by Soul jumping through her bathroom window, seeing the "witch" naked, and Soul having a nosebleed and screaming "BOOOBS!!!". Most parents would be uncomfortable for their children to watch this but trust me, it's fine! The first third of the series or so, is playful and fun.
Death the Kid pretty much dying because his hair was asymmetrical,
Black Star attempting to, ahem, "assassinate" Kid because he "Can't have rumours about anyone but himself passing around the school",
Soul, always talking about being "cool", the super hawt (in my opinion, don't judge me) guy, the musician that played piano in his insanity, the fabulous as all hell demon weapon of Maka,
Maka being a total bad*ss and kicking butt whilst also being top of her class, mastering Genie hunter AND Kishin hunter,
Patty being the adorable airhead she always is,
Liz, the fashionista, being the one to freak out or sweat drop when her meister, Kid, does something reckless or criticises anything asymmetrical,
And finally, Tsubaki, the lovely, caring demon weapon that everyone loves, who tries to make the most out of any situation...
These seven crazy people all make one awesome show, I'd say that Maka and Tsubaki are great role models, Maka always studies hard for her tests, and Tsubaki is a kind and gentle person...
But after the fun, comes the seriousness...
I've read on Wikipedia that the story deviates from the original path in the anime. *Spoiler* Apparently, in the manga, one of the characters, Crona Gorgon, goes insane after killing the witch Medusa. I don't blame him though, she DID perform experiments on her own child. YES, Crona was her kid, she put Ragnarok, the Black Blood/Demon Sword IN him. As blood. Messed up, right? But what's a good story without some insanity?
*Spoiler* But in the anime, Medusa tries to convince Doctor Franken Stein, to join her in her research. She made him go insane, by making Crona put a snake in Stein's weapon's tea. That snake made Stein lose his sanity faster, by being around Marie Mjolnir, he went insane. The irony is that Marie is the one who saved him from insanity.
Like I said, what's a good story without some craziness?
Drugs and Alcohol?
No, not really. No drugs in the series, but there was some alcohol. Franken pretended to be drunk so he could get some secrets out of Medusa, Spirit/Death Scythe got drunk once in a bar(?) and told the viewers a little about his life story. Franken also smoked a lot, as if it was second nature. But it's not like that's super serious.
Sex? Nope. None. Nada.
Cussing? Meh, low level. D*mn, crap, jack*ss. Stuff like that. But in the manga there was sh*t. Just sayin'.
Violence? Like I said, I'm used to blood and gore. But if you compare this to Owari no Seraph, it's nothing! Your kids will be fine, dear parents! *Spoiler* Well, Soul DID jump in front of Maka when she was about to die. He got a huge scar from his left shoulder to his right hip. But it adds to the story.
Consumerism? Dunno what that is, but I don't think that's in there...
Great Messages? I don't think so, it's just one of those stories that don't exactly have a lesson. You know those shows where most episodes, it's just the main character learning stuff, then at the end of the episode they learn their lesson and the teacher is all, "You have done well, I am proud of you..." This isn't really like that.
In other words, if you're okay with a little half nakedness, then you'll be A-okay!
What other families should know