It is free in the UK, for I am there now and downloading. I have started watching ATLA, but find the kids-show-ness of it stops it totally holding mt attention––though I like the world and the characters a lot, especially Katara and Zuko's uncle and the random mercenary gothlady on the giant wolf. Also Appa :). On the basis of your description, though, I think I will like Legend of Korra a lot! :D