Okay, I know I have work to do, but I have to finish out the series. I actually finished reading Extras last night, but haven't had time to sit and blog about it until now.
WARNING: I may give away something about the first three books (Uglies, Pretties, and Specials), and maybe even about this book, so proceed at your own spoiling risk.
After finishing Extras I would definitely say that there is the trilogy, mentioned above, and this is sort of an epilogue. The characters from the Uglies trilogy make appearances, but the real story focuses around new characters, in a new town, with a new storyline. I really, really like that this book takes place in Japan - not many of the books I've read (granted this is self-selection) have taken place in East Asia, and so I was glad to have a mainstream book set there.
Once I got over the disappointment of the story not being about Tally, I really got into it, until the big "shocker" that the story centers around, about a quarter of the way into the book. This very strange thing happens and all I could think was, "wait... what?!". I had to put the book down and take a break to consider if I wanted to continue reading, wondering if Scott Westerfeld had just decided to pull a fast one on the readers. Pulling myself together again, I finished the book, and I have to say, it's worth reading, if you liked the trilogy. That said, I didn't feel as connected to the characters, or their world, as I did throughout the Uglies trilogy. Still, there is a lot of neat imagery, and it is a fast-paced, easy read - something that you can put down and come back to without feeling lost.
I've never read anything remotely sci-fi before now, and I think I could get into it a little more. But, I still have two more books (both the first of trilogies) that my friend lent me, so it'll be a little while before I come back to science fiction.