Been following this pretty closely since it was announced since Avatar is one of my favorite cartoons ever :) It was originally supposed to be 13 episodes, but they changed it to 26, hopefully the growing excitement will make them want to change it again :) iirc Korra learns Water, Earth, and Firebending before the series starts, and has to learn Airbending from Aang's son. Also, according to Avatar Wiki, there was some info about the anti-benders revealed at Comic-Con...
Honestly I don't think it will be as good as The Last Airbender, but it will still probably be fun to watch and WAY better then anything else on Nick.
The anti-benders, called Equalists, hate bending for an unknown reason, but they are also benders <_< many of them can Chi Block (Like Tai Lee) to stop Benders, and they are NOT related to Energybending.
Honestly I don't think it will be as good as The Last Airbender, but it will still probably be fun to watch and WAY better then anything else on Nick.