This episode had a lot to sink in, because it was quite hard, I couldn't really efficiently focus on simple tasks for not stop thinking about the episode, also it let me quite emotional by just remembering the 2 scenes that made me cry, one for nostalgia and other of sadness over Korra, Tenzin and Jinora makes me want to cry again.
It was a beautifully executed episode, the animation was amazing and so the voice acting.
The episode visually and the interaction explained how this whole spiritual energy flows (specially the avatar solar system =D ), it shows how important it is to be calm and keep your mind clear, because if you focus on negative thoughts and emotions, it can affect the energy flow and twist it which affects your surroundings, it kinda works like it does when someone is laughing, even if you don't know the reason why the other is laughing, you start laughing and so do the others, or if in your home in a depressing environment, you become depressed, etc, also show how important it is to stay positive, it's to stay positive when we need most in troubling times, I think it subtly mentions the karma.
Some theories and wondering questions about the avatar world regarding the spirit world and material world, specially about the dead, what it happens to the "human" spirit when leaves the material world by leaving his material body where it goes after, because we always saw the spirits and "human" spirit was visiting the spirit world while their body remained in the material world, so the "human" spirit has to go somewhere when his material body dies, right? so Iroh kinda answered, he kinda talked about death in a harmless and light tone, in a sense to not be scared or bad but embrace it instead and go on, it made me feel nostalgic about this subject such as life and death and spirituality (a subject I always found fascinating, Harry Potter books series quite touches the subject), the way he defines tranquilly, makes me remember a quote of a novel I didn't read, but that it was a wise quote coincided my beliefs that has kinda the same meaning:
"You don't have a soul, Doctor. You are a soul. You have a body, temporarily." A Canticle for Leibowitz by Walter M. Miller, Jr.
Thanks Iroh, for taking away my doubts about the spirit world and material world in the "avatar world". =)
About the events, Unalaq, you are very twisted and very mean, I just don't know if is by greed or by naiveness and tricked by Vaatu or by unhealthy obsessive hope seeing his wife again as some fans theorize it and tricked by Vaatu (yes, I disagree with this theory, it quite resembles Hiroshi Sato obsessive blind revenge on benders, also I hope it won't go that path).
Even though it was kinda obvious what Unalaq wasn't going completely keep his word, I think even Korra thought so, if you think about it, she was hesitant in a serious way thinking carefully, she didn't had much option, she didn't wanted Jinora being infected like she did, Jinora was kept hostage which is better than being infected, because at least Jinora may have chances to save herself or being saved than being infected.
I cried when Iroh appeared, I had some tears in the eye, I didn't sob, I was tear eyed, as for Korra trying to save Jinora and came back to the material world, looking at Tenzin about to cry for feeling extremely guilty for not bringing Jinora and Tenzin reaction, as if his biggest fears about his daughter's safety became reality, you can see in Korra's face what is she thinking: "it's all my fault, it's all my fault, I made a big mess again, I couldn't save Jinora or close the portal, I'm failing as the avatar." - it's heartbreaking, I'm sobbing by just writing this. Korra, don't be so hard on yourself and I feel so sorry for Tenzin. T-T
I think I do know now what will happen to Tenzin in the finale about his realization that he has to face "his own shadow", who will probably overcome it, finally go to the spirit world and try to save his daughter Jinora.