I'm a little torn, so we'll say 3.5 rounded to 4
There were things I really liked about this series conclusion, and things I wish were a bit different but I did enjoy most of the book, and the series in general. What held it together for me were the characters and the fairy tales weaved through all of them.
The stars of the series for me were Thorne and Cress. I loved both of their character arcs and their storylines I wish it was more focused on them and I had more time with Cress. There was a decent amount of humor. Overall entertaining series!