I've read (and struggled with) some Miéville books before. City and the City I enjoyed although I thought the end was a bit too clever, Embassytown I just didn't really understand. So I took a break and then tried this one as it's consistently well reviewed.

It felt like two separate books, there's a first third that felt Miéville-y, the story wanders around introducing characters, Isaac is a slovenly fat eccentric scientist, and has a girlfriend and some associates and we follow them round. New Crobuzon is certainly depicted with a lot of imagination and it feels quite alive.

And then the second part of the book (it is split into seven? acts so I can't use that word) is an action thriller. Some chapters are entirely from the PoV of the leaders of NC, presumably just to otherwise have a gap in the narrative. Isaac we're told is still fat and slovenly but by the end of the book he is firing handguns across rooftops (albeit badly). The character arc of his girlfriend is just weird, unless it's purely supposed to be a gotcha for the audience. And a censored version of the end of the book is "and then they left and got on a boat". It makes Neal Stephenson look like JRR Tolkein.

Maybe I'd enjoy this more if I read it again. Maybe if I'd read it before other books, for example the end of Stephenson's Diamond Age has a similar feeling (to me) of "here is a science term I have heard, and that's the clever trick we're finishing with". But I enjoyed the first two thirds of the book, and then to me it just runs out of steam.