There are many readers out that there that absolutely adore this series and I guess I must have missed something because throughout the entire series I had this feeling of it's good, but I've read better.
The part that kept me reading was the unique setting and the Darkling. To be completely honest, I hardly cared about the other characters. The quest for the amplifiers was also something that kept me hooked. I remember be completely bored for most of the first book until they were hunting the stag, mostly because I found Alina and her friends unappealing.
The main problem with this book is how the ending was handled. There are numerous hints that the Darkling isn't beyond redemption and that maybe, just maybe Alina can save him, however in this book very little good can be seen in the Darkling. He also hardly ever makes an appearance in the book, it was mostly Alina and her friends traveling around with little reminders that the big bad Darkling is still out there. It made the ending less satisfying and would have probably bothered me a lot more if I had enjoyed the rest of the series more than I did.
Not only was the ending for the Darkling unsatisfying, but all the character development for Alina throughout the entire series is more or less thrown out the window. She goes from an orphan to a powerful Grisha to back where she started.
Nikolai is pretty much the best character in this book and the only one that I actually cared about, but like the Darkling, he doesn't have many lines and is hardly ever present. Originally I shipped Alina and Nikolai, but I realized that she hardly deserves him, especially if she's constantly pining over Mal.
If this series had ended differently, it could have been fantastic. I think even some huge fans of this series will be majorly disappointed, especially if they liked the Darkling.