I don't know how you experienced it but when I wached the movie I wanted to feel like it was the first time I was catapulted in this fantastic world.
I wanted to feel what I felt when I watched the first episodes of ATLA.
And what is more important in a new world than a good introduction for the main characters you are going to follow through there adventures?
In the movie, to often I heard a little voice in my head saying "Wait, did he introduced himself yet?", "Are they friends now? because I dont feel like they bounded", "who is that gyu? The firelord? seriously?" (yes, because lets face it, I didn't anderstand I had the firelord in front of me, why would he show his face yet? where is the mistery that is suppose to suround him? and why no one introduced him as the fierced firelord?).
Maybe we should worry more about our favorite trio, and for that, we need scenes to identify with them, we need to see them bounding like friends, playing together, sharing moments, laughs and sorrows. This kind of moments are very rare in the movie and often empty of sensibility.
What do you think about that?
ps: my english isn't perfect, I apologise for that, I'm french and I do my best, Peace!