Holy amazingness. Here's what I thought:

1. At first, it's like being dropped into a sequel. The world isnt just explained right off the bat; you figure it out as time goes on, which is cool and very good world-building.
2. All the characters were highlighted, no matter how long they were in the book. I could give you a list of every character right now...but I won't.
3. June and Day were great lead characters. The whole thing played like a movie in my head. Very vivid, but not too descriptive to the point of boredom.
4. Unique writing style. Very different and refreshing, I appreciated how in this edition, June's chapters were a different color than Day's, it made it easier to remember who was speaking. Both narrators were equally interesting.
5. The plot is just fantastic. Thrilling, mysterious, fast-paced. Never a dull moment.
6. Took me back to reading Divergent and The Maze Runner, however, it was very unique on its own. Very good dystopian elements!
7. We need that sequel! Soon!