I loved this book so much, I don't know where to start. I had pretty high standards going in, since TMI and TID are two of my favorite series, and i was just a little bit worried about whether Lady Midnight would live up to those expectations. 
 I really liked that we got to meet the TDA characters in CoHF, and that we saw more of them in the Shadowhunter Academy novellas. (Side note, if you have not read Tales from the Shadowhunter Academy yet, I would really recommend reading it BEFORE you start TDA. As I said, Emma and the Blackthorns all make appearances and there's a lot of backstory and important character observations that make reading Lady Midnight even better.) 
 I think my biggest concern starting this book was that the characters were going to feel too archetypal. (Like, Emma would be the Will/Jaceish snarky, fierce warrior who's afraid of emotions, Julian would be kind and artsy and Jem-like, Cristina would be more of an Izzy character, etc.) But that never happened; the characterization is this book is FANTASTIC. Yes, Emma is sassy and fierce, but she felt like a very real, distinct character to me. Also, we have the same name, so I'm a little biased towards liking her. What surprised me, though, was how interesting, unique, and well-developed every character in this book was. Julian, Cristina, Mark, Kieran, Dru, Ty, Livvy, Tavvy, Arthur, Malcolm...I could go on forever about these characters and how quickly Cassandra Clare managed to make me care about them. Even when it came to the villain of the story, I was able to understand their motives and sympathize with what had been done to them. 
 Something else I thought was really well-done was the portrayal of mental illness. These characters didn't feel like caricatures, or as though they existed for the purpose of highlighting their condition. They were just as real as the rest of the characters, despite the predictably closed-minded outlook of the Clave on the subject. 
 And the whole parabatai concept...Emma and Julian just made me feel all of the emotions, and I'm sososo invested in seeing how that aspect of the plot is resolved over the course of the series. 
 I could write so much more, but I'll stop myself here and just repeat that I really loved this book.