I advise you to not read this unless you are willing to hear minor spoilers, or, have seen the movie before reading the book, therefore, this review may not give too much away.
Divergent has a simple, perfection to it. The concept is wonderful; the factions, initiation day, etc. I especially enjoy how this is only in one city, as we are told in the first book (hint, hint) and by that I mean the idea of factions and dividing everyone into their personality groups, Abnegation, Dauntless, Erudite, Candor, and Amity.
The author, Veronica Roth started this book years before the first one was published, in the perspective of a young boy named Tobias (Four), needless to say he is in my view the second main character in the books. She abandoned the project, until, she discovered that Tris (Beatrice) would be the perfect character to be the narrator of the story.
All around perfect book in my view!