I read anything that's nailed down, or even just moving slowly. Cereal boxes, candy wrappers, all genres, etc., and I don't always have much time for arbitrary distinctions like literary fiction vs. genre fiction.
This story is set in the cities of Beszel and Ul Qoma, which are fictional but co-located somewhere in the Eastern European/Turkish area our own world. The two cities basically occupy the same physical spaces, but the residents of each city are not supposed to acknowledge or interact with the other in any way or Bad Things Will happen (this is called a breach, which is punished by an all-powerful Breach committee). Into this environment comes Besz Inspector Tyador Borlú, who is investigating the murder of a young woman who is not what she appears to be. The case takes Borlú across to Ul Qoma, where Things Take A Turn and Complications Ensue.
--The world-building. Miéville successfully creates a simultaneous there-but-not-there, tonally distinct feeling in each city. Really excellent.
--The language. I'm a huge Raymond Chandler fan, and this reminded me of his stuff. (I gather this is a departure from Miéville's typical style.)
--The protagonist. I connected with Borlú, a good man who's just trying to do his job, bureaucracy be damned.
--The secondary characters aren't particularly fleshed out, particularly Borlú's counterpart on the other side and his female colleague on his own side.
--The plot gets bogged down by the end. After I finished the book, I had trouble remembering who did what to whom among the red herrings and false starts.
I'm glad that I read this book, but I don't think it'll be sticking with me for the long haul. Your mileage may vary, of course.