This is a great book for people getting into YA scifi/dystopian, with a bit of romance. I love the action and the moral questions, with an enemies to lovers trope. I will say that the fourth book is not good. The ending to Champion (#3) destroyed me, but it was good, and Rebel (#4) was not nearly as good, I think it was just a book for the fans who wanted closure, which I personally think we got but some didn't enjoy. Great book, everyone who likes YA should read it. I'd say youngest about 10-11 years old, if you are ok with a bit of romance.