Other than one ongoing plot line, I think this book is better than the original, not that the original was bad. It gets off to a bumpy start as it course corrects from the ending of the first book, but soon settles into a well-paced story. That course correction is necessary because the ending of the first book was written before the second book had been plotted, when it wasn't clear whether or not there was to be a second book. The end result is a couple of chapters at the end of the last book, and the beginning of this one, that serve no useful purpose to the overall story.

About that one plot line:
Mal and Alina are in a toxic relationship, but the author doesn't seem to realize it. Yes, both the Darkling and Nikolai are trying to poison it, but it would be toxic even without their meddling, or rather, their meddling wouldn't have much effect if it wasn't toxic to begin with.