The Legend of Korra is an excellent edition to this magnificent series. It's full of surprises, action, and of course humor. The only thing I don't like is that they don't go out of the city and explore the world (like the original). But it still holds up as the original! Oh, and they've improved the animation! :) I suggest you watch this series. But if you've never watched this series I suggested you start with the original (The last air bender).