It's fine. I can see why Candlewick is really excited for this book; it's crisply written, it's got a lot of quirk, and its Dickensian influences are fairly obvious.
But like, that's it. Its racial metaphors are poorly defined and the problem with it being a pretty clear Dickensian send up is that Dickens did a lot of this already, and it doesn't improve on some of his faults, like "good" characters who aren't particularly defined in their "good"ness. I get that memorable villainous characters are a Dickens hallmark, but his "good" characters have always been incredibly bland and this book doesn't improve on that. The villain is fleshed out in this one, which is an improvement. She comes with motivation, bitterness, and backstory, but her good sister is just good! Just good! It made me feel overwhelmingly sympathetic to the villain, but it doesn't even use that unfairness as the reason she deserves some empathy. It ends with a trite little "she was small once", like a lifetime of neglect and overt favoritism shouldn't probably be discussed more extensively? Especially when it's clearly the defining aspect of her past? I'm fine with "cool motivation, still murder", but her motivation is barely even touched on outside of the book telling us what it is. Considering Phoebe is such a total non-entity in this book, probably could have used that to flesh out both the sisters as opposed to just dumping it in the middle of the book and then having Phoebe be this randomly angelic pure being with no personality who wanders in 20 pages before the book is over to give it a happy ending.
At the same time, I rarely felt a special-ness to Dickens characters, and Arthur is covered head to toe in it. The book is like "you're the Wonderling!" at the end, and I was put off entirely. What does that mean? Is that good? I assume so? I assume that it's good and special because Arthur is the main character, but that's the only reason. What IS a Wonderling? Should I care? I don't know and the book is over! So I don't! I guess people were waiting for him and he's special and stuff. His unique ability helps a bit in the book, and could be making a point about language and culture divides but if that's what was intended then the poor racial allegories I mentioned earlier make it a little muddled.
It's fine. It's a fine book. It's just fine. The only reason I don't give it 2 stars is that I recognize that it's only me being incredibly unimpressed by this, but it's... it's fine. That's just. All it is.