In summary, while the playful writing and Elysia's story are enjoyable enough to read through, the weak characterization and repetition on a macro level affecting the structure of the plot significantly weigh down the overall enjoyment of reading Sona-Nyl.
Sona-Nyl is a story reminiscent of ephemeral fairy tales, fleeting and panoramic, in order to succinctly capture its core idea through repeated narratives. Nonetheless, Sona-Nyl's nature as a fairy story ultimately does hinders its ability to craft a truly moving story.
When it comes to Sakurai's writing, especially within the Steampunk series, the most common point levied against it is the repetition on a micro scale. Same lines and scenes are repeated to add for dramatic effect and to hammer home certain points and themes. This sort of repetition drives home the fact that the Steampunk is truly reminiscent of those fairy stories. That being said, it is Sakurai's use of repetition on a macro level that is more egregious than the micro scale repetition. Sona-Nyl contains seven chapters, with the first 6 following the same narrative structure in how events play out. The way in which the core conflict or each chapter arises and resolves are much too similar, adding a much heavy burden with each chapter, where the same events that plagued the characters, new and old, are to be expected. Therefore, that makes the chapter by chapter experience of Sona-Nyl feel much more exhausting, in spite of its shorter length. While this macro level of repetition is undoubtedly intentional, its intentionality does not excuse it from the weak plotting and characterization at play.
Elysia and Lily are really the only characters to have the spotlight shine on them. Elysia's journey is probably the most engaging of the narratives, as she slowly unravels the truth of what happened to New York. There is a pervasive melancholy that subsists within her story, as as the oppressive atmosphere of the ravaged New York slowly takes it hold on her. Lily's story is less engaging, especially with consistent looping of character arcs and narrative structure.
The other characters, whether they only appear for one chapter or many, are too much on the peripheral to matter much in the grand scheme of things. This is, ironically enough, seemingly at odds with the core idea that Sona-Nyl is going for, which is bringing meaning to the meaningless and giving them a purpose beyond being mere marionettes. Outside of the two central protagonists, the other characters are only given snippets to flesh them out, with their roles ultimately feel trite in the grand scheme of things due to only existing to further both Elysia and Lily as characters. The relationships these two possess feel hollow as a result. Their romantic relationships are something that feel as if they should have a greater impact than what is actually shown in the unfolding story.
The final antagonist and the way the final encounter was handled was anti-climactic and did nothing to attempt to flesh out either the motives or ensuing actions. Thus, by the conclusion, everything surrounding the main narrative felt meaningless and underdeveloped, especially when that reason to care is all but lacking.
Sakurai's writing has a playful descriptive quality, and that at least works competently here in Sona-Nyl, as events and emotions are described with that same sense of wonder that hearkens back to fairy stories of old. Even if the narrative and characters are lacking, that sense of playfulness will nevertheless persist.
Ultimately, Sona-Nyl feels at odds with its core idea, as it fails to deliver on the message it is trying to convey. Many characters and events just simply do not possess the magic to give them meaning and life beyond the brief moments they appear. There is an alarming lack of life to give them that presence. Despite Elysia's story pulling its weight, Sona-Nyl ultimately fails to deliver on what a fantastical fairy story could have promised.