Interestingly enough, this ended up being my favorite book of this series, though it truly is an "extra" in every sense of the word, rather than being a typical sequel. I just found the "reputation economy" of the city in this story interesting to read about, not to mention the latest technological innovations that Westerfield presents.I also found the characters to be a little more likable in Extras. Their weird language didn't annoy me the way it did in the past two books--mainly because it wasn't as pronounced as it had been. Speaking of likable characters, one of my favorites in this book wasn't even a living being, it was Aya's hovercam, affectionately named Moggle. Another quirky, fun character is Frizz, who has a crush on Aya despite the fact that she is still an "ugly" and is the founding member of Radical Honesty, thanks to the brain surge he had that doesn't allow him to lie. I haven't even mentioned the Sly Girls or Aya's brother Hiro and his friend Ren, but they all make up a strong supporting cast for Westerfield's final installment of the Uglies series.This story is initially about Aya's quest for fame and a higher "face rank." Ah, the face rank... one of many aspects of Westerfield's fascinating reputation economy. You can earn merits for doing chores and other everyday helpful things and your face rank moves up based on how much people are talking about you. At the beginning of the book, Aya's face rank is a dismal 451,396... the rank of an "extra." Of course, by the end of the story Aya and her friends are on an exciting adventure to save the world, with the help of none other than Tally Youngblood. If you enjoyed the first books in Westerfield's Uglies series, I highly recommend Extras. It is a bit of a departure from the others, but another example of strong storytelling and fun reading.