Such an ending!!! 
This series has always set itself apart because there were not truly happy or easy things: yes they saved the world, but they lost lots of people. We saw the girls go from strangers, to reluctant companions, to friends, to finally a family; all while having fights and relationships and lies and secrets and being teenage girls (always difficult even if you're not a witch).
This book goes deep into other characters some who we already met: I loved Viktor's progression,  Gustaf (who I love wholeheartedly), Rikard and Evalina (great new additions without much spoilers) and the always secretive Mona. And some new that I loved: Clara (whom I just want to hug), Walter (and his strange influence) or Felix. 
So I am sad to see this series go, (specially when I feel there was so much potential for at least a little time forward novella with the ending) but sometimes it's best to let go than to extend it. All in all a perfect book