This is really one continuous narrative split into three separate volumes owing to the impossibility of containing the thing within a single binding, although the previous two volumes break at natural breathing points in the story at the expense of creating books of equal size (and the first two are a bargain at the price, even though they make the third look puny).
In terms of genre, it sits in an awkward place where the retronym expansion of SF, speculative fiction
, is probably the only umbrella to adequately cover it. The prominence of dukes and fencing and hunting in the story tend to align it more closely with fantasy, which is funny, when you think about it, because all of those things clearly were and are real enough. A very
early reference in Devices and Desires seems to indicate a magical system of theology where miracles can be redeemed for hours of religious devotion, which is never referenced again and may be a fossilized remain of an earlier conception. In fact, something which happens quite late in this volume allows the reader to fairly definitively situate the setting as postapocalyptic, but clearly nothing that is revealed at that late stage can be said to define the genre of the preceding narrative.
Vaatzes the engineer gives the trilogy its collective title and gets a substantial portion of the page count narrated in his point of view, but I don't see him as ever being one of its protagonists, and would argue that he is hardly even one of its characters. He's part of the setting, part of the giant speculative what-if that sets up the story.
It's a fascinating way of telling a story, full of multiple redundancies and precision detail. The sort of thing that would appeal to an engineer, in fact.