This was a very, very long book. There were two or three points where I thought the story was going to end, but it just kept going. Most times it was fine, but there were parts where everything just dragged along.
The characters were okay - I think the strongest written characters in this book were Amber and her husband, a man that she originally didn't want to marry. Their story is pretty tragic, and I was upset that by the end of the book we weren't sure how that particular story line ended. I've got to wait until I can get the next book to find out if Amber is still alive. I'd assume she is, though. She seems a bit too important of a character to just kill off and not mention it.
Killian was also a fun character. While he started off as the villain, he broke away and started making his own choices. I ended up liking him a lot more than I thought I would.
I loved the mythology behind Essence. How it works, why it works, what it does, what it CAN do...a lot of thought was put into Essence, and it definitely shows. My favorite parts of the book were those that delved into how each House uses the Essence to create their specialties.
I wish more had been explained about the Evermen. Throughout the story, all you really find out is that the Evermen left behind the books explaining how Essence works. Who were the Evermen? Where did they go? Why did they go? Did they even really leave? None of these questions are answered. Perhaps more answers will be given in the next book.