In a word: Wow. Sarah J. Maas's Queen of Shadows is truly epic, full of action, blinding plot twists, chaos, heart break, and characters I have come to adore. In terms of sequels, this is a great one. There isn't much I wanted more or less of. Once again, I'm totally impressed by this complex story with its flawed heroes and epic plot line. 
 I'll try to keep my review brief, since so many eloquent reviews have already been written on Goodreads and various blogs. 
 A note: I think it's important to try and read The Assasin's Blade prior to reading this book. There are characters, plot devices, and entire relationships constructed in that collection of novellas that I feel would have been much less impactful in QoS had I not previously learned about them. 
 What I loved: I enjoy reading Sarah J. Maas's books as a writer and a reader. There's no question in my mind that she is an excellent author, and I think with each ToG book, her writing has become better. My favorite element of this series so far has been Aelin's journey. She goes from a shallow, unlikable badass in book 1 to a literal queen in book 4, and watching her dynamic growth has been such a great adventure. I love that she is flawed. That she is selfish and self reliant, that she trusts herself more than anyone else, and that she learns to become a fighter for the survival of not just herself, but an entire nation. She's truly one of my all time favorite characters. 
 I also love Aedion, although his character fell a bit flat for me in this book. He's fiercely loyal, brave, and ready to fight for Aelin at any cost - even though at one point (view spoiler)[he feels betrayed by her choice to make a blood oath with Rowan. (hide spoiler)] The friendship and deep familial bond between Aelin and Aedion was refreshing and important, and I actually wish more time had been spent fleshing out their relationship. 
 In terms of relationships, I also enjoyed the friendship between Aelin and Lysandra and Manon and Asterin. I barely cared about Manon in HoF. But in this book, she becomes interesting and likable, and her plot line finally twines enough with Aelin's that I didn't mind it interrupting Aelin's journey. 
 Finally, I loved most of the plot lines. Sarah J. Maas is a conductor of chaos, and her plot lines are like notes of music weaving together and floating apart. My main problem with HoF was that it was so long, and so little happened, and all of it felt very separate. But in QoS, each event felt knitted together in a smooth, exciting way. I think that's why I had a hard time putting it down. 
 What I didn't enjoy: I know this is probably a massively unpopular opinion, but I just don't connect with Rowan. (view spoiler)[I appreciate the romantic subplot, as I think Maas writes romance very well, but I honestly haven't liked him since I met him in book 3. His relationship with Aelin is volatile and violent, they are over-bearing and over-protective of one another, and he is so emotionally closed up that I don't really see how I could ever connect with him. Now, I do understand that this is fiction, and his nature (and Aelin's) are due to the fact that they are Fae. I'm just saying for me, personally, Rowan is not a favorite. (hide spoiler)] 
 Along those lines, I'm also gutted about Chaol. I was so, so surprised at how incredibly short changed - and boring - his story line was. In books 1 and 2 he was a vibrant, strong character. (view spoiler)[But in this book, he's almost unbearable. He's self-loathing, guilt ridden, and brooding. Yes, I know he lost his position and his best friend. Yes, I know losing Celaena hurt him. But I really don't think he got any decent treatment at all. Aelin's anger and guilt toward him feels outrageously unjustified, and I can't believe that fury carries through this entire book. I mean, she even tries to blame him if Lysandra gets killed? And in the end, Chaol is the only character who suffers an injury that isn't magically healed. An injury that could end his career. It honestly felt like his "relationship" with Nesryn (which was so confusing) was only added as a consolation prize for readers who loved Chaol, which only frustrated me even more. (hide spoiler)] 
 My last grievance is that there are so many characters. I put the book down every time Elide's chapters came around. Likewise, I couldn't bring myself to fully care about Nesryn, Kaltain, or even Lysandra. I totally understand and respect the POV changes Maas orchestrates. But throughout, all I really wanted was to read about Aelin and Manon, and how their plots intersect - not Rowan, not Elide, not Lysandra, not even Aedion. Honestly, even Chaol's POV got old. I guess that's the risk of multi-POV stories, though. Not everyone connects with every character, and I think that's ultimately ok. 
 Overall: Despite my grievances, I think this is an excellent book and a solid sequel. Everything I didn't enjoy about HoF was erased in this novel, leaving me with an exciting, page turning story with plot twists at every turn of the page. Aelin is an incredible character with an epic journey, so no matter how long a book is or how far her story stretches, I'll be happy to follow. Even if I disagree with little things along the way. 
 I think Maas's writing, and this series, are definitely worth the loyalty I feel for them.