I really liked this book. There were certainly problems with the science behind it and we never got all the answers..how they hell does Ruth find Madame & Miss Emily? However, the voice was great, I loved the way things unfolded (trying to figure it all out just as the kids had to figure it out; knowing but not having been told). I didn't think the whole love-triangle between Tommy-Ruth-Kathy was very believable; Kathy and Tommy were too similar (and certainly wouldn't push Ruth for either of their own interests), but I thought they made better friends than lovers and always had. Rather than "missing their time" I thought they were forcing it at the end. Overall a great quick read; some thought provoking moments about the morality of clones and a bit reminscent of Octavian Nothing (a sub-par human used for experimentation). The tone reminded me a bit of Scott Westerfields' UGLIES.