As someone who loves the Avatar series but was kinda disappointed by F.C. Yee's previous two installments to the franchise- The Rise of Kyoshi and The Shadow of Kyoshi - let me say I loved the turn-around here with the Yangchen duology.
In the Yangchen novels, F.C. Yee really took the premise of writing a character who was already somewhat fleshed out by the original series and expanded upon her greatly using unique little story tricks and writing details we haven't seen from the series yet.
The Yangchen novels manage to steer away from a lot of what I found to be the failings of the Kyoshi novels, like choppy pacing, writing cliches, and too large of a cast of characters for everyone to really feel fleshed out. The pacing is much smoother, I wasn't able to call every shot the plot was taking, and rather than having a massive ensemble, the story really focuses on two characters- The Avatar, and her her newest companion- and really fleshes out both of them to be fully believable, lovable characters despite their flaws and horrible decisions.
This is played into the fact that a large theme of this story is trust, and trying to learn to rely on other people amidst the chaos of grand political strategy where allies are just as easily offed as enemies in the name of self-gain.
That isn't to say the story doesn't have its flaws- where the Kyoshi novels felt like too much foreshadowing, there were moments and details in the Yangchen novels that felt like they had been forgotten, something being repeatedly introduced and brought up but never really paying off in the story.
Thus I'd rate this novel;
★★★★☆ (4/5 Stars - I'd recommend this novel to anyone who is a fan of the Avatar series, and while maybe Avatar: The Last Airbender is the better place to start for the series as a whole, this is still a strong standalone. If The Last Airbender wasn't your thing, you might enjoy this airbender instead.)
I'm going to attach a rebug of this post with a Spoiler, because everything beyond this point is going to be a much more of a deep dive into the plot that may be filled with actual spoilers, so read on only if you don't mind learning more coherent details about the story.