An excellent show for teens.
Soul Eater is an anime about a group of students at a special fighting school fight and defend people against evil demons. A lot of the show is about teamwork and trusting one another, and in one episode the main character, Maka, makes friends with a misunderstood enemy instead of fighting him.
The violence isn't full of gore, but sometimes there is a lot of blood in fights. Blood is also used in some of the most minor injuries, usually in a comedic way. Characters are stabbed in the chest, punched, cut in half, etc. Expect lots of violence between good and evil, often with lots of blood. Characters sometimes fight each other, or hit each other on the head but these are never serious. Make sure you're okay with blood and violence if you're watching.
As for sex, there are occasionally jokes about boobs or skirts, and a rather comical scene where a father asks his friend to buy his daughter a book for her birthday, but his friend accidentally ends up buying panties and a tiny bra instead and gives it to her, much to her disgust. Once a character flips up another character's skirt, to her embarrassment, but nothing is shown. Characters never have sex, nor is it implied. A few times a character will be shown in the bath, where you can see cleavage and legs, but no real nudity is shown, but it is implied.
Adult characters sometimes are seen at bars, or drinking wine, but they are not drunk, though one pretends to be once. A main character is a scientist that smokes often.
There are scary scenes, for example there is a demon that is trapped in a bag made from it's own skin, and as it escapes the skin can be seen stretching around it's unseen body from within the bag. Some monsters are fairly creepy.
As for language, there are frequent uses of "d*mn", "h*ll", "b*stard". No uses of "sh*t" or anything worse.
All in all it depends on how mature or experienced you or your child is to decide whether they should watch the show. Children under 13 would probably be too young to understand the plot or the jokes geared toward the older set. If you're okay with violence, blood, and occasional mild sexual jokes, this is an excellent show.
What other families should know
Great role models
Too much violence
Too much sex
Too much swearing
Too much drinking/drugs/smoking