Aya Fuse is an extra, a face-missing nobody. In a city of a million, where the economy is based on fame, her face-rank hovers at about 450,000. The higher your rank, the higher your prestige; if you can become a celebrity, you can have all the resources and friends you want. Aya has been trying to follow in her older brother's footsteps, becoming famous by being a "kicker," or reporter. Too bad none of her stories interest anybody...
Until the night she sees some girls pulling a dangerous stunt. The Sly Girls are subverting the fame economy: they are trying to be unfamous, having secret adventures instead of seeking attention. Aya knows that kicking their story will make her face rank soar, and so she infiltrates the Sly Girls along with her sidekick hovercam, Moggle. But Aya quickly discovers that her story will be about much, much more than a few risky pranks... including the potential end of the world.
Disclaimer - I've read the Uglies trilogy, to which Extras is sort of a companion novel. So I understood the background and world-building, more so than somebody reading this as a stand-alone story. You might enjoy it more or less on its own, I don't know.
But I loved it.
Extras does a good job of staying unpredictable and interesting. It's a unique plot, with some amazing world-building. I liked it quite a lot.
Aya was pretty relatable and realistic, although (I felt) not particularly likable. Hiro, Ren, Frizz, and the Sly Girls were all fascinating, multi-dimensional, and just plain cool. And Moggle, although maybe not technically a character, was also pretty awesome. The characterization was amazing.
Very well-written, and I love Westerfeld's style.
End Result: five stars. And excellent book. Read it.