I dithered between three and four stars for this. I think it's on the low end of four.
On the upside, this is much better than the usual steampunk mess. There's a complete absence of silly romance, nothing is unnecessarily or unrealistically made of brass, nobody wears a corset, and there's at least one character with depth. It's not a 1930s pulp in a bad Jules Verne costume, either, and it isn't littered with basic editing errors.
Having said that, there are a few issues. Firstly, while obviously steampunk, by definition, isn't about real technology, if you have a steam-powered technology and you somehow supercharge it by using a magical fuel, you don't use that fuel to replace the water in the boiler. This suggests a lack of grasp of the basics of how steam engines work. (The author tells me she said the same, but it's a shared world and she was outvoted.)
Then there are a few Inigo Montoya words scattered here and there. "A pastiche of stone and bricks" used to mean, by the context, a patchwork. "Ascribe" used to mean "subscribe". "Betook" used as an archaic word for "took", which it isn't; it has its own meaning, which makes no sense in the sentence where it's used.
There's also the Whole Culture Used Only as Flavouring Problem, in which a culture from our world with complex historical origins is grabbed and used more or less to provide a bit of colour, without much in-depth understanding. In this case, it's the German culture, which provides mainly names (or the general shape of names; I don't think most of them are actual German names or mean anything in German). One of those names, von Sülzle, in our world would indicate aristocratic descent (because of the "von"), but it's given to someone who's very much a commoner - and shows this by talking like a modern American, in contrast to the more formal speech of the rest of the characters.
So much for the language and setting. I'll note again that this is still much better than the average steampunk work I've read.
As far as the characters go, I liked the protagonist, a gentle scholar from another, ancient city, mourning his little sister, excited to be a part of rediscovering history, missing his cultural food and drink. He had depth and dimension and remained consistent throughout. The antagonist, by contrast, seemed to become the antagonist out of nowhere, without adequate foreshadowing, and I found that offputting.
It's always revealing, to me, when I set a book aside for a while and read something else instead, or entertain myself in other ways rather than read it, and this was such a book. Partly that was because, having hit some of the flaws mentioned above, I was dreading it getting worse (it didn't). Partly, it was because it got dark in places, and that's not the kind of book I prefer. Mainly, though, I think it was the lack of something: a vivid and compelling story problem presented early that would grab me and not let me go. There definitely is a story problem, but I felt it came too late in the book to really seize my interest.