In this book a world is created then torn apart. In this respect it reminded me a bit of Perdido Street Station, which I found more unnerving (terrifying, giant moths) and in the end more melancholy. The major difference is that Embassytown is a far more fragile settlement, it's a human settlement that relies entirely on the cooperation and technology of the native alien Hosts (Ariekes). The story is told entirely in first person by Avice Benner Cho, a woman from Embassytown who was one of few inhabitants to leave and go out to other planets. The first part alternates between present events and flashbacks so that Avice and the world she grew up in are introduced to the reader.
Once we are familiar with Embassytown and how it works -its links with the Host aliens, its bubble of breathable air, its upper class of Ambassadors (fully identical, linked, doppels/twins)- a paradigm shift happens and everything goes to pot. The society that was built up faces a major catastrophe and descends into desperation and barbarism and war. The book is about the people who carry on trying to keep things running in the face of likely destruction. It's about how there will still be factions and politicking even in the face of disaster.