Bravely Default takes place in the fantasy world of Luxendarc, focusing on four protagonists: Tiz Arrior, Agnes Oblige, Edea Lee, and Ringabel. They end up traveling together for various reasons, Tiz: to help rebuild his destroyed village, Agnes: to fulfill her duty as a vestal (it's similar to a nun), Edea: to spite her father and his army, because she disproves of their violent and sadistic practices, and RIngabel because he is an amnesiac and has nowhere else to go.
The story is quite deep and fleshed out, so are the characters. The game itself is quite difficult, actually, I started on normal difficulty but had to turn it down to easy. Which is saying something, because I have a lot of experience with RPG's.
The combat system is fairly easy to pick up, although a younger kid will have a very hard time, as the game requires clever, intelligent, and strategic use of the system. You can't just spam and expect to win. Put it this way: it's not Pokemon. You do really have to plan out moves, consider all your options and opportunities, look for weaknesses, anticipate your enemies' actions, etc.
It also has a very beautiful art style, and the characters are absolutely adorable. The whole game is eye candy. A treat to look at. And the soundtrack is amazing. Matter of fact, I have a lot of the game's music on my iPod.
My only concern with appropriateness is that Ringbel is often going after women and flirting, there is also a sage that takes it further and invites Edea and Agnes in to bed with him. There's also a lot of talk of sexyness and sex appeal, and a few scenes focus on a very racy and skimpy bikini that one of the girls ends up wearing. None of it is extreme, there is no sex or nudity, and if your child is mature, they should be fine. The game is too lighthearted to make a huge deal out of those topics.
Overall, though, it really is a great game. If you're looking for something to play, try Bravely Default.