If you haven't read 'A Million Open Doors', stop now. Go read that, and find out about the Thousand Cultures of humanity and the attempts to reunify them now that the 'springer', the hoary old sci-fi gimmick of instantaneous transport, has put them back in touch.
OK, so now to EMOG. The main characters of AMOD, Giraut and Margaret, are sent to the bum-hole of the universe, an isolated world with little habitable land and two mutually antagonistic cultures, one Tamil and one Mayan. The progress of their diplomatic mission is set against their attempts to save their marriage and the results, while not remotely unexpected, leave you with a sense of sadness and horror.
A beautifully painted book, with wonderful descriptions of the clashing cultures and a supporting cast that are more believable that the protagonists. It made me feel as if I was in high-tech version of 15th century Asian or American cities: definitely worth a read.