I really wanted to like this book. I really enjoyed the first one, which made the second one worth reading. If this series were longer than three books, I would call this one the first of two bad books which would cause me to stop reading the series. The book isn't bad bad, but it is merely okay, which would be the first of two consecutive strikes needed for me to stop reading a series.
The book starts nine after the last one ended, with a dead robot left on Earth now working, Americans terrorizing everyone under the guise of "freedom," and our four intrepid heros returning from Esat Ekt. The storyline also folds back to immediately after our four Earth heros landed on Esat Ekt and are not allowed to leave, so we learn their history and why they left when when weren't really allowed to leave.
It's easy to see where Neuval was going with this particular book: he talks about us versus them and repressed populations and people being held against their will, stopped from leaving by a bureaucratic government and power-seeking people. The parallels to modern western culture and its direction are almost punched into the reader's face.
With Kara gone, however, the sass of the conversations are gone, too. Which makes the book less interesting. There isn't discovery and adventure, there's the tedium of life and the mundane. Both of which, sure, exist and are important, but not when I'm reading a young adult science fiction books about aliens and giant robots and the like.
And really, if it is so easy to recreate a person, memories, soul and all, why wasn't Kara xeroxed in this way and updated regularly?
If you're reading the series, read the book, finish the series. If you're not reading the series yet, read the first book at stop.