Ian McDonald, Ares Express (Pyr Books, 2010)
You will know whether you will love or hate Ares Express long before you have finished the first chapter. The litmus test is very simple: what is your reaction to the name of the main character. If you find Sweetness Octave Glorious-Honeybun Assim Engineer 12th to be painfully twee or flat-out incomprehensible, then you will hate this book. There are roughly forty-seven thousand impossible things in Ares Express, starting with a beloved uncle who got turned into a signal post by a brief fluctuation in reality, and if you can't deal with the heroine's name, you're almost certainly going to have no patience for flying zeppelin churches, sadistic hunters of human furniture, giant shoe sculptures and the people who explode them, and the World-Devouring Squid.
If, on the other hand, you dig the possibilities for glorious, unfettered insanity that Sweetness' name portends, then you most likely love this book. After all, a name that precarious deserves a book equally as ambitious, and this one certainly qualifies. Start with McDonald's first novel, Desolation Road. Make a hard left at magical realism, a sharp right at pulp, a quick turn into the neighborhood of Mars as imagined by everyone from Burroughs to Bradbury, and then make a left turn at Albuquerque, and you've got Ares Express or a reasonable facsimile thereof.
But it's Sweetness' story, in every sense of the word. Early on, a chance encounter with a mythical figure -- and yes, on this Mars that sort of thing can happen, because it's really all Marses, and, well, it's complicated, but you have to go with it -- informs Sweetness that she's now the heroine of a Story. This meta-knowledge is something Sweetness wields to glorious effect, first running away from an arranged marriage with someone from an entirely different caste of Trainfolk among whom she grew up (As a female, Sweetness would never be allowed to drive the train she grew up on, and don't think that doesn't come into play sooner or later) and then having all sorts of marvelous adventures as a war for the reality of Mars itself unfolds around her.
Needless to say, Sweetness' desertion sets off all sorts of aftershocks, many of them involving her venerable and tough-as-nails grandmother. There's magic. There's swing music. There's a war in heaven waged with AI saints and robot angels who can alter probability, and there's the evening news, all in one rollicking package.
If a reader can deal with that -- can get behind the glorious insanity of Sweetness Engineer 12th and all of the mad scientists, dreammakers, lost boys, diamond roof pirates, giant furniture artists, professional practical jokers, trainfolk, invisible siblings, time-stealing cardsharps and Flying Edsels she encounters along the way, then Ares Express will be a positively joyful read. If they're looking for consistency, hard science, rational behavior or the minutiae of the hypothetical Martian railroad system, they're probably going to be disappointed.