It took me a few chapters to get into this book but once you get into it you're kind of stuck. In a good way.
The characters are great, I love the way the author slowly introduces the different factions instead of giving you a lot of information at once.
At the end of this book you still don't know everything about the different factions but there are two more books. You do have all the knowledge you need to understand the different reasonings that come from each faction in this book, I did not find myself wondering about certain things because I didn't know everything about the factions.
I particularly liked that Tris is not saved by a guy and instantly falls in love, she is her own person and the relationship that devolps is written so well.
The same can be said for all the relationships in the book, from parent and child, friends and romantic relationships. They never seemed forced and all of them grow with the characters and the story.
I liked how this ended, giving you a real end to the book but not to the characters story. There is no huge cliffhanger that they put there to make you have to read the next book.
Even so, I have the next book to read.
Great story, wonderful characters.
Highly recommended.