Well, I guess I didn't hate this book as much as most people. I think this was because I had read a lot of reviews beforehand and kind of knew what to expect. Was the book an unnecessary piece to the overall green rider story? Probably. Was it a bit strange that Britain went steam punk on us? Definitely. But, because I had been forewarned I was able to read the book for what it was, a separate piece of work. Yes, some of the things that happened will have an effect on future books but for the most part this was a stand alone interim book while Britain figured out how to continue with the "real" series.
One major problem I had was the thing was just to damn long! 700 or so pages for a book not really connected to the series was a bit much.
I did like that the connections of the characters from both "worlds" as it may be. I enjoyed the story. I had trouble remembering who some characters are since it had been so long since I read the previous book in the series, but again, since this was more of a stand alone than anything, it didn't matter that much.
All in all, I can fully understand people's hatred of this book, but I found it an enjoyable, if semi-pointless, read.