I imagine most folks who keep up with sci-fi and fantasy got to this one before I did, but in case you haven't, I'll just say that the cover blurb by Charles Stross is truth in advertising: "Lesbian necromancers explore a haunted gothic palace in space! Decadent nobles vie to serve the deathless Emperor! Skeletons!" By turn snarky and serious, and sufficiently dark for my palate without being dour.