Miéville writes beautiful descriptions. Everything else about this book was a slog to get through, from the monologues he has characters give in the midst of battles to the repetitious similes. Another annoying tick: characters had (incredibly obvious) realizations and then spent pages thinking about how much their mind was blown. Yes yes, we get it, your whole universe is rocked on its axis by the very idea that, say, a spy might have collected plans for an invasion. Let's get on with the story, shall we? Oh no, we have to spend at least three more pages reading descriptions of how this totally shocks you? All righty then.
There were some bits here I really liked, like Tanner's conflicted feelings about the ocean deeps, or the idea behind the scabmettlers. The ideas
behind Miéville's societies are good, but he doesn't follow them up well--I still don't know how a single character ate, or where they got their clothes, or anything like that. There wasn't much foundation to the world building, just a lot of flash and wordy purpley description.
I got annoyed that not a single female character succeeded at anything. There are exactly four female characters with any page time: Bellis, who is literally only useful as a conduit for male characters' actions. She translates what men (and the Lover) say to other men. She takes a book from the man who found it and gives it to the men who want it. She's manipulated by Silas Fennec to get information from Uther Doul and vice versa. Fennec gives her a letter which Tanner actually has the adventure of delivering. On and on--there literally is not a single instance in this entire book in which Bellis does a single thing of her own accord. She's delightfully cold, misanthropic and lonely, so I assumed I'd love her, but her incompetence and unending supply of naivete really annoyed me. There's Shekel's girlfriend, who doesn't do anything except provide Shekel an opportunity to get over his prejudice against the Remade and Tanner a chance to show off his engineering skills. Carrianne is Bellis's friend from the library, who has about three lines, no plot purpose and mostly serves to introduce the idea of the goretax. And there's the Lover, who has I think two monologues and that's it. To add insult to injury, after the fact we realize Uther Doul convinced her that they need to get the power of the Rift, which was her driving force through the entire book, so even her motivation isn't her own. In the end, she's deposed rather randomly and vanishes off the boat. Every other character is male and every single goddamn thing that happens in this entire goddamn book is driven by dudes. It is dumb and it started really straining my ability to believe the world.
As for the plot...well, it's very episodic and poorly paced, and the main characters are completely useless within it. I had a really hard time maintaining interest in this.