The Scorch Trials all in all was a very well-written book. You can see the challenges that the characters have to face and understand the situations that they have to go through. The characters model teamwork, perseverance, determination, and so many more positive attributes. Yes, one of the characters does "betray" another character in a selfish manner, but you can also view their situation through their eyes and understand the purposes behind their actions.
There is A LOT of violence in this novel. It can get dark, but depending on the maturity of the reader, they can understand the content and how the characters in The Scorch Trials deal with these situations and come together to escape them. Some of the violence never actually occurs and is really processed in their imagination by WICKED. (SPOILERS!!)
As for the language, the occasional cuss word is used, like crap. Most of it is made-up slang, like slint-head, shank, or klunk. The language isn't a major issue, once again depending on the maturity of the reader.
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I (13) personally enjoyed The Maze Runner more than The Scorch Trials, as did my brother (11). We both thought that yes, this book is well-written, and yes, there is a strong plot line throughout the story as well as deep characters. We can say that some of the violence was irrelevant, but added more depth to the characters as well.
I would recommend this book for 12-13+. For younger readers, it's fine as long as they are mature, understand the content, and can discuss the content. Thank you.