Wow. This is what I've been waiting for from LoK. So many questions, and so much excitement.
I'll keep this one short, and hopefully mostly spoiler free, since the episode just aired.
The animation; so much better. The music; incredibly nostalgic (as was hearing Roku speaking). The episode was, surprise, rushed. But only because they could have made an entire series out of this, and it would have been great. I love lore and backstory, and this really delivered. Better yet, it really added a lot of weight to the conflict in the present day. After last week's revelation about Varrick, well... suddenly that seems like small fries.
I'm not even upset that we haven't seen Tenzin in forever, or that we didn't see much of the Fire Sages at all.
Does Unalaq know about Vaatu?