Mockingjay, by Suzanne Collins.
Ending things is hard: ending TV shows is hard, ending movies is hard, ending novels is hard, and ending novel series is especially hard. But Suzanne Collins has managed to end her Hunger Games trilogy well, with a pretty good final novel.
My favorite part about this series is that the books were not carbon-copies of each other, and Mockingjay certainly stands out from the first two. While The Hunger Games is an action-adventure movie in a vaguely political setting, and Catching Fire is a political thriller with action-adventure elements, Mockingjay is flat-out a war movie. It is about strategy and tactics, and ends in the inevitable confrontation.
I appreciate this genre change, as the characters remain consistent from book to book to book. The changes that Katniss, Peeta, & Gael experience in this final novel are reasonable, given where they started, and how we've seen them mature and change over the first two novels. There is a moment at the end that was totally unexpected to me, but was true to Katniss' character. And I took that moment as a very interesting political commentary, one that young people would do well to learn.
And now that I have finished the book trilogy, I can move into watching the movies with a clear conscience.