First off, for those of you new to China Mieville, I would recommend that you begin with "Perdido Street Station" (or "King Rat"), followed up by "The Scar", and only then tackle "Iron Council". While the three books don't form a trilogy in the traditional sense, they nonetheless draw on shared themes and a common setting and history. As such, while "Iron Council" can certainly be read and appreciated by a newcomer to Mieville's writing, there are numerous small references and commonalities that will be missed.
Fans of Mieville, however, will find in "Iron Council" perhaps his most nuanced and sophisticated writing to date. As usual, the author defies genres, and has produced what would best be described (if one was forced to use labels) as a gothic-western-political-thriller. At the same time, he continues to subvert traditional fantasy elements as well as co-opting elements from other traditions and grounding them in his reality. However, Mieville has also tackled a more challenging structural approach in this novel, as he uses three different voices and two time periods that, while connected by plot threads are separated by decades. Furthermore, the chronologically earlier section comes 130 pages into the book, which in the hands of a less gifted writer would be horribly jarring, but which Mieville pulls of with style.
The primary story (which is elaborated upon by the flashback) is set some twenty years after the events of Perdido Street Station, and finds New Crobuzon at war with distant Tesh, with discontent at home mounting as the casualties mount and the economy falters. It is a time of turmoil and political dissent bordering on civil war; as options are weighed, one man, Judah Low, goes in search of a near mythical construct whose time may be at hand, Iron Council. To say more would risk severe spoilers, but the real joy of "Iron Council" is that the plot is served so deftly by the underlying themes, and vice versa.
And those themes are legion, the most obvious one being New Crobuzon's war with Tesh as a parallel with the Iraq war. Likewise, there are economic factors that are akin to the bursting of the .com bubble of the late 1990's. However, Mieville has made it abundantly clear in numerous interviews that he has no interest in spreading his political views (he is a Socialist who has run for Parliament) through his writing, and that holds true here. Rather, these elements serve to ground the story in a believable reality, which allows the reader to accept at face value the fantastic elements. Moreover, even as he subverts everything that is a "norm" of fantasy, Mieville also casts his own views in a realisitic light. For example, the political activists (with whom he obviously sympathizes) frequently make capricious, even brutal decisions, and display very un-liberal traits such as disdain for homosexuals.
However, as I said, these groundings are mere jumping off points for a much more intriguing exploration, for at its heart "Iron Council" is an exploration of change/history. The groundwork for this is laid in Judah's ability to create golems, which Mieville describes as an intervention, a decision to change the un-living to living. Once the reader recognizes this metaphor, Mieville's intent becomes clear as he considers industry, politics and war (among other things) as interventions into the status quo, as forces for change. In so doing, Mieville quite rightly takes a long view of history in which right and wrong become blurred by the law of unintended consequences. There is a symmetry in his world, almost karmic in its nature, in which actions in the past rebound in unexpected ways in the present. The driving force of history for Mieville is the individual, but as such, he recognizes the fundamental instability this introduces into his novel. People change, there motivations change, and as such, tipping points can never be quite predicted, and will often radically diverge from the expected path.
Which brings me to one of the most intriguing structures in the book, that of the quest. In traditional fantasy, characters will generally band together for a come purpose, and face adversity from outside of the group. Their internal dynamic is largely fixed, and their motivations are common. Mieville, on the other hand, has described two quests in which each character's motivations are different, are often hidden, and sometimes at odds within the group. This far more realistic approach allows him not only to paint a more reasonable view of historical change as described above, but also to consider the power of "truth" as a motivation for said change. Mieville argues that sometimes a myth or a symbol can be more powerful than the truth. However, there is a danger in myths because they can be twisted to mask one's real motivations. Movements for revolutionary change, and one need look no further than the French Revolution, often become dressing for personal vendettas.
Finally, Mieville takes these two intertwined threads, intervention and truth, to ask an ultimate question: can one work for change even as one despises the mechanism of said change. For example, is murder acceptable if it serves a greater good? Or does change always pervert the purest motivations and draw them closer to that which is being rebelled against, in form if not in ideology? Does hating war mean wanting your country to lose?
In conclusion, if I have created the impression that "Iron Council" is nothing by dry philosophizing, I must apologize as nothing could be further from truth. First and foremost, "Iron Council" is an adventure story set in a world that for all it's bizarre and beautifully realized detail is nonetheless disturbingly familiar. However, Mieville is such a gifted writer, who pours so many ideas into his work, even the most literal reader will find themselves drawn into the undercurrents which suffuse the novel. "Iron Council" is another brilliant contribution from a remarkable talent, and I strongly recommend reveling in it.