June and Day, though they're the same in many ways, lead wildly different lives and have entirely different perspectives on the Republic and the book's split-POV narration portrays this so well. Because of getting both perspectives there's a big difference between what the reader knows and what the main characters know; this makes the story even more tense, which is definitely a good thing as certain big plot points in the book are fairly easy to predict, which means that a lot of the story's strength has to lie in other aspects: the characters, pacing, setting, and stakes.
It's often difficult for me to become emotionally invested in a dystopian novel - with the notable exception of The Hunger Games trilogy, not many in the genre have been able to tug at my heart. This book is the exception. The love between June and her older brother, as well as her profound sadness at losing him and her need to bring justice, is not only seen but felt. At one point early on I almost thought I'd have to quit reading because her emotions were so sharp and the story so sad. The fact that Day's story was just as touching only made the tension between them, between his wants and hers, even stronger.
As far as plot goes, though the smaller plots flowed great, with pacing that added plenty of tension, the larger plot points, mostly involving the nefarious activities of the Republic, were easy to predict. While this was a definite problem in the book, the slow world-building and questions about how the Republic came to be ultimately overwhelms the predictability. With characters that are easy to connect to (not only Day and June), true emotional content, and high stakes, this is a book I'd definitely recommend.