The Quantum Thief, a 2010 science fiction novel by Hannu Rajaniemi, was difficult reading for me, as I kept feeling like I was reading a foreign language I wasn't fluent in. It rewarded my persistence, though, and I enjoyed the experience. According to Wikipedia:
The Quantum Thief is the debut science fiction novel by Hannu Rajaniemi and the first novel in a trilogy featuring Jean le Flambeur. ... It is a heist story, set in a futuristic solar system, that features a protagonist modeled on Arsène Lupin, the gentleman thief of Maurice Leblanc.from the back of the book:
The Quantum Thief is a crazy joyride through the solar system several centuries hence -a high-flying adventure and a mystery novel in one brilliant, speculative package. Every morning upon waking, Jean le Flambeur must kill himself before his other self can kill him first. But on one such average day, Jean is rescued by the mysterious Mieli and her flirtatious spacecraft, broken out of the Dilemma Prison and taken to the Oubliette, the moving city of Mars. The Oubliette is a city of ubiquitous public-key encryption, where a moon-turned-singularity lights the night and people can communicate via shared memories. Meanwhile, human investigator Isidore Beautrelet, called in to investigate the murder of a chocolatier, finds himself on the trail of an archcriminal, a man named le Flambeur...Locus concludes,
Indeed, in his many lives, the entity called Jean le Flambeur has been a thief, a confidence artist, a posthuman mind-burglar, and more. In his last exploit, he managed the supreme feat of hiding the truth about his self from the one person in the solar system who is the hardest to hide from: himself. Now Jean has the chance to regain himself in all his power -in exchange for finishing the one heist that he could never quite perfect.
Rajaniemi is having as much fun with these characters as with his gonzo physics, and by the end of the novel we’d be willing to follow them down any of the several sequel-corridors that Rajaniemi gives himself. For now, he’s spectacularly delivered on the promise that this is likely the most important debut SF novel we’ll see this year.SF Reviews found it difficult to read, but says, "It's all very intricate, and to be perfectly fair, a jaw-droppingly impressive future in its construction." SF Site calls it "clearly one of the best SF novels of the year" and says, "Rajaniemi has quite successfully met the expectations his short work had raised."
The Guardian opens with this: "There are science fiction novels that impress and those that entertain. All too rarely the two come together, but in this baroque theft caper, Hannu Rajaniemi has pulled it off with aplomb. That this is a first novel makes his achievement all the more notable." Kirkus Reviews closes by calling it "Spectacularly and convincingly inventive, assured and wholly spellbinding: one of the most impressive debuts in years."