On the level of first reactions, it's mid. There's a lot of telling but not a lot of showing. I see the effort that went into the setting, but it doesn't quite feel cohesive enough, because the logic of the world and narrative skip around. A couple of the reviews draw comparisons to Alice in Wonderland, which are very accurate in terms of structure, but perhaps not in terms of character effects -- Alice is a fish out of water; Russell naturally fits his environment.
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But that's not quite it, is it? The kaleidoscopic world is fine if there's some interaction between it and the character, but somehow these interactions, including the unprompted violence, fall strangely flat. This may, of course, be part of the point -- the main character is, in one sense or another, beating his head against the asylum walls; he does not have agency, and his inability to impact the immediate environment simply reflects this.
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Though if we're on the subject of agency, about halfway through the book, I realized that it is thematically similar to Bioshock Infinite, and came out about a year after the game. The comparison to the game ends up somewhat unfavorable to the game: here we have a quest for the anima, the dark father/alter-ego, the light alter-ego, the child alter-ego, the temptress, the self-deception about the relationship to the setting.
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And saying it this way obscures the bigger point: the canonical archetypes are drawn with a broad brush, but their depth is limited; to some extent, the book relies on symbolism too heavily. It's fine if everything is a symbol, but if those subjects also have no independent existence, the narrative becomes weak. Yes, I get that them having no independent existence is the point of the plot. The goal of the book is to create an impact despite that.
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The violence against women is darkly gratuitous (but makes sense with regard to the themes), the violence against children is comically gratuitous (and thematically relevant in theory, but pushes the book into bizarro fiction territory), the racism is apropos of nothing and underbaked (I suppose it makes the main character look even more despicable, but he didn't really need the help).
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So what does it get? Well, I went in with no expectations (except maybe "Ligotti-esque setting"), I thought the execution was rather weak, but it was fairly fun to read, and I'd say I enjoyed it more than the 2-star books, and I would be fairly interested in reading Corrosion (which every other review says is more accessible) next time I try to get into modern weird fiction. So 3 stars it is.