I rarely finish a series, even if I love the first book, because more often than not, second (third,...) book is just not as good; with few obvious exceptions (Harry Potter, anything by Rick Riordan, Eragon, Lunar Chronicles). This series is one of those exceptions, for me. 
 I love Sara and Nicolas and love reading about them. I love the banter, love/hate relationship, how they slowly grow closer... no insta love there :). In the second book Sara is in the Mohiri compound, struggling with training and felling abandoned by Nicolas, who left soon after getting her there. She slowly make friends. The story really gets fun when Nicolas gets back. He becomes her trainer and helps her feel more at ease there. 
 There is a lot of action, with mysterious Master lurking right around the corner and enemies come from all sorts of place. 
 My favourite part of the book, is watching Sara develop her power, both Fae and demon side. She still struggles, but a lot less than before. As with the previous book, side characters are essential part of the story too. I love the family and friendships. Only missing part of it is Remy. :) He was one my favourites from the first book. 
 Highly recommend it!