The Golden Spider and The Silver Skull are both fairly paint-by-numbers steampunk: it's vaguely Victorian-ish, with the ton & the peerage and all that, but there are Babbage cards and steam mechanicals and such too.
The Golden Spider is probably the better novel, following a girl scientist trying to stop a killer and cure her brother and also there are spies.The Silver Skull relies on one of those "we have to pretend to be married so we might as well bang" scenarios, which I find tedious, and I didn't buy the reasons for the lovers to be apart anyway. But bonus points for pteranodons that the evil lady saddles up so she can have sky battles with airships. That was fresh.
What I really wanted to say about this series, the thing I found utterly charming, was the epically nerdy science behind both of these plots. A science that was lovingly detailed with so much legit scientific terminology that I would just start skimming at points as the principals breathlessly talked chemistry at each other. The author's bio states that Renwick has a PhD in chemistry, and it shows: she loves this shit; she's not going to dumb it down; and she's going to work out the science plausibly, even if it's fictional.
Hard science is very rarely my thing. I simply do not care about verisimilitude, unless you wrap it up with some actual characters, which doesn't happen as often as I'd prefer. And generally I'm not reading steampunk for the articles, but because I like the dash-punk pulp aspects: I want to see me a fucking kraken, or an airship battle that crashes, burning, into the sea, or some automata struggling with sentience. But here, in books where the steampunkery was wan and drab, I lived for the nerdy stuff, in a weird reversal. It just goes to show that the enthusiasm of the writer towards the subject, be it chemistry or krakens, goes a long way toward my enjoyment of a novel.