I read Perdido Street Station several years ago and loved the worldbuilding and the frantic, multithreaded plotting. The Scar continues to explore the diverse and fascinating world of Bas-Lag, but Mieville's plotting and pacing don't really work as well for me. 
 The worldbuilding, plot, characterisation, and descriptions feel very out of sync. Main protagonist Bellis Coldwine, passenger on a ship that gets commandeered by pirates from the floating city of Armada, but she spends a great deal of time doing very little aside from absorbing the world around her. It takes the book hundreds of pages to really pick up the main thread that carries through to the end. Along the way, Bellis and another protagonist named Tanner Sack occasionally experience bursts of agency, but are otherwise mostly blown around by decisions that happen off-screen. If they're lucky, some other character will arrive to lecture them about the (genuinely fascinating!) world. 
 In a way it's nice to have a story that's about small people who aren't in control, because we ourselves are mostly small in the grand scheme of things. But between that and the author's elaborate descriptiveness (which he's very good at, but it does go on), the first half of the book proceeds at a glacial pace. It does pick up, and there are some genuinely stunning passages and enthralling ideas in the closing act, but I couldn't help but feel that some of the most interesting things were happening off-screen, being portrayed at arm's length, or being drip-fed to the reader. 
 Still, worth reading for more of Bas-Lag's mad inventiveness, and I quite liked Bellis even as I felt bad for her disempowering situation.