I enjoyed Perdido Street Station a lot, but my favorite novel by him is 'Embassytown'. It's about the power of language and very thought-provoking. It's a completely different kind of novel, though, and doesn't necessarily appeal to fans of his Scar stories.I wasn't able to really like the other books I tried from Miéville, which I read after being blown away by Perdido Street Station, but I devoured that one.
Perdido was a bit too gloomy for my taste, but it's chock-full with intriguing ideas. It reminded me favourably of Iain Banks' Culture novels which share this quality. Lesser authors don't put that many ideas in a dozen novels.