A pretty impressive return, and a lot of fun moments. We get to see the world expanded further, not only geographically and culturally, but in terms of getting to know Korra's and Tenzin's families more. Good action, good music, good animation, good new voices.
A couple of things bug me. I'm not happy that they just fobbed off all the first season's loose ends with a simple "It's been six months and Republic City is at peace." The Equalists wouldn't have gotten as far as they did if there weren't a strong core of discontent among non-benders about their treatment by benders, and that's something that would take a long time to address. It feels like a bit of a cheat just to brush it aside like that. Although maybe they'll do a comic-book miniseries filling in the gap sometime.
It also feels like small-universe syndrome to have Korra's own father, who we thought was just some guy in an igloo, turn out to be the former heir apparent to the Northern Water Tribe's chieftainship and the general who caused the spiritual imbalance now racking the world. Having all the most important characters be related to each other is usually a rather contrived trope. Although it occurred to me that maybe the reason the Avatar's soul passed to Korra was that it was her destiny to correct the imbalance her father caused.
I pegged Unalaq as the bad guy pretty much right off. Despite his seeming benevolence, he's clearly a fanatic, and he's got sort of a Tarrlok-esque quality, a sinister undercurrent to his surface helpfulness. As soon as we saw that he had the power to calm the spirits, I suspected that he was the one who stirred them up in the first place in order to provide an excuse to convince Korra to train under him -- and, as we later saw, an excuse to bring the Southern Water Tribe under his control. Note that the first spirit attack 20 years earlier resulted in his older brother being banished and Unalaq inheriting the chieftainship. (Plus his twins are rather creepy. Bolin has strange tastes.)
Not happy that Asami disappeared in episode 2. I assume we'll see more of her and the crazy financier guy later on. What I'm wondering is why his moving-picture starlet Ginger is a redhead. They don't have Caucasians in their world! How have they ever seen a redhead before?
Interesting that Jinora was spiritually drawn to the hall of statues, and to the one statue that I think must've been Wan, the first Avatar. Looks like she's got some of the spiritual sensitivity that Korra lacks. Maybe she'll be able to help teach Korra.
Actually it feels like they reset Korra's personality a bit. I'd think that after her experiences in Book 1, she would've learned to grow a bit beyond the "punch everything and ignore the spiritual" behavior. She should've already understood that she had to try to connect to the spirits rather than just fighting them, even if she wasn't very good at it yet.
Hey, wait a minute. This takes place on the winter solstice in the south, and it's been six months since the end of Book 1. And
Republic City is in the north. That means that Book 1 ended on the northern winter solstice, i.e. the season took place in the fall. It looked more like spring or summer to me.