One of the best things about this book was that it didn't rely on the same old tricks presented in the first one. The second best thing was that I was able to read it without any confusion despite the fact that it had been over a year since I read the first book.
Clare has a wonderful imagination, and I was amazed by her ability to world-build. There's some teenage angst here, but for the most part, the book is built around a solid story. Valentine, the bad guy in the series, is very intriguing. Yes, he's a cold-blooded monster, but strangely, a monster with a specific code of ethics. In a way, I found myself not agreeing with him exactly, but at least understanding why he was doing what he was doing. That's what makes him so frightening.
I also liked how the young people in the book worked alongside their elders. The teens are very self-sufficient, but they're not above calling in help from their parents and guardians. That is to say, they may take crazy risks, but they aren't stupid.
I can't wait to read book #3 in the series.