To be consistent with other rankings this should be a 5/5.

I have just re-read this book, having mostly forgotten what it is about, and really really enjoyed it.

At the science level, humanity is still confined to the solar system (if one calls the Oort cloud part of the solar system). Some humans are wildly augmented, but most are still DNA based biological forms as nearly as I can tell. Most of the story takes place on Mars. The book is heavy on mathematics and physics: prisoner's dilemma, quantum entanglement, and cryptography all add to the plot.

At the political level, there are multiple factions, one of which may or may not be responsible for the disappearance of Jupiter. Mars is a reasonably closed world, unwelcoming to foreigners, although there is a colony of zoku, political refugees from inter-planetary war, descended from a colony of gamers.

At the personal level, Mieli is a native of Oort, extorted into rescuing Jean le Flambeur from prison. Jean himself is a legendary thief and once resident of Mars. To earn his freedom, he has to help Mieli find something that he has hidden from himself, for reasons that he has forgotten. Meanwhile on Mars, Isadore helps the Gentleman solve a murder involving the taste of chocolate. Little do any of them expect to become entangled with each other, and with conspiracies that extend throughout Martian society and possibly even beyond.