I saw the first 2 episodes. Korra is annoying as hell, I understand they are making a strong female character, but her whole personality sucks asses, I would like this kind of self centered personality in a more lame character, but it's really annoying in her because she is the avatar. Typically this kind of personality get changed when clash with reality, but fuck, she is the avatar, she literally bends reality.
And the 2 brothers are so plane characters, they look like something you would see as a typo character with no real role on the story. And the deal is that this is not even making a comparison with the character of the previews avatar, because when you do, you can see a step back on the quality of the characters personality. Now this can be because it's not planed to be a long serie, so making elaborated characters would challenge the deadline of the serie; it also can be that the characters might go deep in further episodes, but really, their first appearance is nothing like when you first met Soka, Katara, Aang and Zuko.
I like that the city looks like something in the 30's and there are cars now, I also like that there is a movement against benders. Still, characters at the moment are very weak and they don't really drive me to keep watching (still I will do, with hope to eat my words and find the serie become better than what it is now).