So which side are the good guys and which are the bad guys? I suspect neither, and I like it that way. Surely it's true Elodians were some hardcore assholes and that's why they were eventually defeated by others and the rest were placed in a ghetto, but at the same time it's clear the Mare side isn't exactly perfect (discrimination, ghettos, killing lil' girls in cruel ways, etc). In fact I suppose they were in the same situation as inside the walls and the history books told a truth slanted to 'the truth of the winner side'. And still at the same time it's clear given how it's told to us that Grisha misinterpreted the 'secret true history books' and his super-positive interpretation is also wrong.
The truth is somewhere shown in this image
with several groups and factions, waging war some times and having peace other times, no side being especially innocent. The normal in human civilization, you know.
And now that I think about it all this gives more sense to some past chapters, as they are two sides from 'outside' trying to get the Coordinate power, it wasn't all a monolithic faction. Things about Ymir's past, Annie's dad, Bert and Reiner reactions and instability (there was truly brainwashing going on which clashes with their years infiltrated), etc.
What else. The start is interesting, there is a contrast on what Grisha wrote at the end of the previous chapter, 'I came from outside, where life is harmonious for humanity' and how this chapter stars, the part of the armbands and the warning about the walls is already ominous. The moment of his sister's death, though brief, is pretty sad, if the anime reaches that part someday it can be a powerful moment. And his turn to extremism and joining the Revivalists makes sense, while still leaving some degrees of freedom to later in the plot mature and change his personality, as we know it happens.
Question, Who is 'night owl'? Daina Fritz or another person of the hidden royalty? It provided the Revivalists not only info while being infiltrated in Mare, but weapons, money, etc.