The Promise has soooo many problems, these being the main ones. It might be easier to list the things that seem legit about the comic:
The Fire Nation colonies being a difficult situation that a lot of varied groups of people have very strong opinions about & are willing to throw hands to settle in their favor.
All the assassination attempts on Zuko.
Mai dumping Zuko. Sucks for him at that moment, but it does make sense from her vantage point.
Zuko ending up with some serious ideation issues from the lack of meaningful support and opposition from literally every possible angle (and the difficulty of trying to undo a century of wrongs pretty much single handedly, and the lack of sleep).
Also him doing a shit job of communicating that to people who are supposed to be his friends/family but aren't around at the moment.
Ozai giving sociopathic advice.
Katara being smart enough to clock that Aang's idea that "all nations must remain separate" conflicts pretty strongly with his desires to a) repopulate the Air Nomads and b) ever be in a romantic relationship.
Aang never having thought about the nature of national identity, given that he was a child being trained in his safe homey temple, then suddenly awakened & off on his training-and-dictator-overthrow quest, and now finally arrived at the point of this comic. Aang is many positive things, but "deeply philosophically minded" is very not one of them -- which is completely understandable! He's 12! He's been through a ton over the past year-ish! This never had to matter for him before!
Suki being a smart, observant, and good friend as best she can.
Zuko doing what he believes he must for his duty (defending his people in Yu Dao)...
...but also trusting Aang's judgment of his actions more than his own, given that he is well aware Ozai would have done the same.
That sweet-looking dragon helmet Zuko has for a few hours before it falls into an opening in the earth. Way cooler than Ozai's phoenix king helmet.
Return of morality coma! Or maybe just his body finally deciding to get some of that lost sleep now that he's exhausted and safe has done his duty. EIther way: sure, that's in character.
But yeah, the way this goes down is depressing.
