I can see why some people aren't fully taken with A Court of Silver Flames but I loved it!  It's by far my favorite book in the A Court of Thorns and Roses series.

Although she can be prickly at times, I have always liked Nesta.  As a main character, she is much more interesting than Feyre.  She is able to carry the story on her own without it always centered on who she is dating at the time.  I still can't forgive Rhysand for some of his actions under the mountain in A Court of Thorns and Roses.  Cassian seems like a far better mate, especially since he gives Nesta the space that she requires.

If you are planning to read A Court of Silver Flames, you should know that the first 300 pages or so are much more character-driven and the plot doesn't start until around page 500.  There is enough action to make up for it in the final 250 pages of the book, but a good portion in the beginning is spent getting to know Nesta and the new characters that come into her life.