I think I'm three behind on his books at this stage, not even counting his children's book... but the other books set in Bas-Lag (the Perdido Street Station world) are very good. The Scar is probably my favourite of the three. Iron Council is also pretty good - among other thing, it's a clever pastiche of a number of different kinds of story - but a lot of people get turned off by how heavily political it is. (Miéville is very very Marxist, as far as I know.) It didn't bother me too much.

The City and the City is very good. I've heard it described as a police mystery by Kafka (I've not read Kafka, but I've heard this a few times). It's set in contemporary Earth, rather than a fantasy setting. His short story collection is also good - there's one Bas-Lag story, and a few horrors. I started Embassytown and it seemed promising.

The main issue with Miéville is he adds a lot of concepts and doesn't explain them clearly until well into the book, if he even outright explains them at all - that works to the book's advantage sometimes but I found it a little tough in Embassytown.

Huh, that means I've read only half his adult books! Better catch up!