Well, I'll just say what I said earlier in a thread on the subject.
I feel that Season 3 is on to a good start. Korra feels like she has grown as a result of what happened last season, but she's still Korra. She still has a temper, and leaps before she looks, but you can tell she has calmed down a little and does listen to those around her. Korra truly wants to do the right thing, of course she always has, but she seems like she has began to truly become the Avatar in more than name.
I like that Asami and Korra seem to have grown closer and become friends. And can even joke about their ties to Mako. Though, I wish Mako weren't being quite so emo. Bolin is still a joy, and it feels like he has more of a purpose than he did is Season 2, where he was just kinda there without adding to the story most of the time. And when Mako and Bolin met their long lost family, I really felt for them.
Seeing Old Man Zuko was just plain awesome and I loved every minute he was on screen. It's nice to see one of the old Gaang taking action in the series. And his comment about "Sparky Sparky Boom Man" brought a smile to my face.
The group that is coming together as villains seems like they need a little more screen time, but their abilities are impressive and they certainly do promise some great fights.
The fight choreography is great as it always was and the animation is fluid.
My only other thing is that the Earth Kingdom seems like it's as bad as it was in Season Two of The Last Airbender. Seriously, it looks like the Avatar will need to do like Kyoshi and completely alter the government again.