I have to say that this not my favorite series so far. I tend to hate things that are way too serious.
The previous series was happy in overall tone and mood. It had some downer moments, but it was mostly upbeat. Aang, Katara, Sokka, and Toph were upbeat people that remembered to have a good time whenever they needed to.
The Legend of Korra starts off in a downer way and it does not let up from there. Korra wants to be the youngest avatar to master the elements, apart from Aang. Having skewed priorities from the get go will lead to trouble down the line.
I’ll probably hold my judgment until later on in the series.