Okay, scratch what I said. That artwork is insanely awesome. I'm buying all three books. That is EXACTLY the kind of dark, morbid, and including the gallery art, occasionally perverse art I love. Fantastic stuff.
They WILL be my next purchases.
ETA: I notice on the website Holly Black praises The Child Thief - she's not much of an author herself, but I love the style of her books (morbid fairytales) so much that I love them irrespective of poor writing. So that's another promising sign.