Much like the first one in the series, I can see where some people would really really like this book, but it just wasn't totally my thing. It was all right - I read the sequel because I had gotten both of them before reading either, and I wanted to finish the story. Unfortunately (for me), it doesn't really seem like the end. I'm not sure if Westerfeld is planning more books in this series, but there are plenty of open plot lines.
It's a very tech-y kind of sci-fi, with lots of intricate details about space weaponry and battle tactics. If you're into the hardware, you'll probably like this.