I was lucky enough to get an ARC of this and it didnt disappoint! This book picks up soon after the events of Obsidian and focuses on the aftermath of Daemon healing Katy. There are lots of differnt things going on in the book, so it was very unpredictable and there is never a dull moment. The pacing is great and you wouldnt want to put the book down once you've started. The plot was quite orignal and it introduced a lot of new things about the Lux and the DOD. We even get to learn more about Dawson and Bethany and what exactly happened to them. I wont say anymore, cuz i dont wanna spoil it, but i LOVED it. 
 Katy was a wicked heroine and i could totally relate to her. She is smart and funny and even when she made decisions that i wasnt sure about or they seemed too reckless, i still supported her because she's not one of those dumb heroines and she can take care of herself. She became totally kick ass in this book and i enjoyed seeing her grow into a strong character. Another reason why i like Katy so much is because of her love of books (totally relatable) 
 Daemon, ofcourse, was as HOT as ever. I really liked him in Obsidian,but he was kind of a jerk at times, but in Onyx he completely won me over; he is now in my Top 5 YA Crushes :) We got to see a more caring side of him and i totally melted everytime he was in a scene. He was very funny and his chmistry with Katy was electric - i swooned everytime he called Katy 'Kitten'. Their relationship goes through a lot of ups and downs which was a bit frustrating because i just wanted them to be together and stop arguing over dumb stuff. Nevertheless, i liked that because of that, Daemon showed how much he cares about Katy and admitted his feelings for her. 
 Some new characters were introduced - the most significant is Blake. I didnt like him at all, but his scenes with Daemon were totally HILARIOUS! I laughed my head off everytime Daemon called him by the wrong name or threatened him cuz Blake was pissing him off - again. Blake is the definition of douch bag and i really wanted to smack him everytime he pulled another dick move - and he did that a lot. Dee was amazing as ever, though i wish she had been in the book a bit more. 
 The final showdown, was EPIC!!! There were 2, actually. The ending was killer and i cant wait to see where Jennifer takes us from where she left it. I NEED BOOK 3 NOW!!!! If you loved Obsidian, then prepare to be blown away by Onyx, because it is that GOOD! And, if u love yourself some Daemon/Katy hotness, then you wont be dissappointed because they have plenty of steamy scenes ;)