Since I'm one of the few people who are actually paying attention to this, I'd like to make my review on this.
Spoilers from here
It was a really good ending to this story. Seeing Toph and Lao reconcile was really sweet and seeing her students step up as metalbenders was really cool. I didn't expect the refinery and the town to still be there. I thought that Aang would convince everyone (including Toph) that some traditions had purpose and that the human settlement had to go. But I guess that it was for the best. That land is probably going to become part of Republic City anyways.
As for Tienhai, her story was interesting. Apparently, she thought that the seashore was boring and that the city made things better there. Falling in love with and marrying the man who would become the king was not what I would have expected from a spirit, but it was romantic. And her statement about spirits never dying but instead taking new forms made me wonder about the original Moon Spirit, Tui, and how Princess Yue actually got involved with the whole thing.
The festival at the end was not what I was expecting, but kind of nice. And it was appropriate that it become not only an Air Nomad festival, but a festival for the other nations as well. The only thing that I would have added was a flash-forward to 174-5 AG, with Korra, Tenzin, and the rest of the cast celebrating the festival with the spirits around them in whatever that town becomes by that time.