Yeah, I felt Un Lun Dun was weaker Miéville. Kraken is better (by which I mean I remember some of it rather than none of it), but still relies overmuch on a lazy, conventional kind of magic. The works of his that I'd really recommend are The City & The City (shorter, clever, and in some sense not even sci-fi) and the Bas-Lag series (Perdido Street Station et al) (long, high but non-tolkien fantasy, plot that was clever enough (at least for me). Mostly I love the worldbuilding so maybe not for people who don't value that as much as me).