Anansi Boys is one of my favorites. It has scary bits, but there are lots of lighthearted and fun bits to balance those out. There's a lot of depth, and much to think about, but you don't need a serious background in comparative mythology to puzzle out who all the characters are, there is more than enough background material included in the book for everything to make sense. I suspect that a deeper understanding of African mythology would make the book even more interesting, but it isn't necessary.
Fat Charlie Nancy is living a totally unremarkable, and rather boring life. He has a boring little flat in London, a boring little fiancee who only started dating him because her mother disliked him so intently, and and extraordinarily boring little job. Fat Charlie is enjoying his boring little life, and fantasizing about how wonderful things will be once he and Rosie actually get married, right up until the day his irascible and thoroughly embarrassing father manages to die in the most embarrassing way imaginable (at least to Charlie), and is revealed to have been not just any old man, but in fact Anansi, the trickster god of African & Caribbean mythology. Also, Charlie discovers that he has a brother, Spider. Spider is the exact opposite of Charlie. Spider has no fear of social situations, and commonly has a string of women dangling off of him. He doesn't have a job, but he does have lots of money, and he appears to have inherited all of their father's magic. Spider waltzes right into Charlie's life, moves into his spare room, steals his fiancee, ruins his job, and lands him in jail. Charlie attempts to retaliate, bungles things horribly (with the help of some little old ladies who really were trying to help), and they both wind up on the run for their lives from some supernatural beings who are well and truly pissed off with Anansi. And don't mind taking this out on his sons. Charlie and Spider team up and eventually manage to overcome the supernatural threat to themselves, and then sort out the rest of the situation. In the process Charlie learns a lot about himself and all the things he has been repressing because of who his father was. It is a fabulous and hilarious adventure as well as a wonderful story about the power of stories.
Ultimately though, I think this is a coming of age story. But not a teenage story, it is the coming of age of people who already thought they had found their place in the world - except that it was the place they had wound up as a result of their parents, their community, and their own fears. It is about bursting free of artificial confines and becoming the person you actually want to be, deep down, doing the things that make you feel most alive, even if they scare you sometimes. It's about not letting yourself be defined by the bad things that have happened to you, and letting yourself love people, even if you don't always like them.
The story is wonderful. Lots of action, lots of insanity, wonderful little bits of magic. A lime. Fabulous characters. This is one that I will read over and over again, like going to visit an old friend.