Mr. Dashner rounds out the trilogy begun in The Maze Runners and continued in The Scorch Trials. These are of the YA genre that seems to have escalated in popularity in recent days--bad adults put young people in serious danger for some perceived good or order in society. It is understandable why they appeal to young people, because we all remember the times when the adult world was out to subvert us and to harm us "for our own good." But it does become a trifle tiresome after a while, and this third book of the series bears this out.
While the series ends, it doesn't seem finished. This last book seemed somewhat overlong and rambling without really getting to a critical point. Mr. Dashner seemed not to know where he wanted to be with the book--Teen Angst or ZA (Zombie Apocalypse--for those not up on the terminology). As a result, the book seemed a bit of a muddle to me.
However, if you've read this far, you'll want to finish out the series, so enjoy. A light enough read with a few annoying aspects (language and plot) but it completes the story.