The final battle was well written. I loved when Cassian opened his can of whoop-ass on the field and showed just how incredible a fighter he is, despite all his joking around. All in all, the relationships between the major characters are what I loved the most about this series. When Amren sacrifices herself to burn the fleet, when Nesta throws herself on Cassian, when Rhys dies and Feyre freaks out... Man, this book was an emotional whirlwind for like the last 200 pages.
While I found the plot development a bit shaky and didn't really care about the new characters, I still enjoyed this book quite a bit.