The plot, in brief: Taya is an icarus, a human categorized into the job she loves as metal-winged courier by the analytical engine, programmed by punch cards, used to run the city. One day, she's in the right time and place to rescue two high-ranked exalteds from certain death when there's an cable car (or 'wireferry') accident. The exalteds, in thanks, give her social access to their caste, one she would otherwise never have a chance to so casually interact with, for all the icarii stand, as a rule, outside the heavy-handed caste system within which the city/nation runs. There are mysteries involving terrorists, there is action and politics, and there are a difficult set of brothers whom she comes to know as a consequence of it all.
One of the book's strengths is how tactile it is, how physically aware of space and strength and motion. The mechanics of flight inform and shape the aerial interactions, the feel of wind, and the weight of bodies. The city, Ondinium, had a strong sense of shape and detail without ever making me wish I could follow along on a map. The complexities of programming are not overdone, and are reducible, in part, to physicalities because they are visible in punch card form. In part thanks to ozarque's past posts on the general dominance in language of sight and sound over touch, I was delighted in many ways by the way Pagliasotti so effectively integrates touch into her world's interactions.
A few times, parts of the overall shape of the plot was blindingly clear, predictable, but at such a macro scale that it did not spoil the details and complications of how the plot worked out in practice. This was a rare book in which I did not find the occasional use of Latin distracting. I did find the Yeovil Mountains a little distractingly named - but they are rarely mentioned.
This book is the best thing to come to me out of my SFR project yet. It feels like it could easily become a comfort read - that level of accessibility - but at the same time, it is not, in its details, at all a simple book.