I'm not really sure why this book has such a high rating on Goodreads. It was alright, but definitely nothing to take my breath away. I've seen comparisons made between this book and the Hunger Games, but this book is, in my mind, far less exciting and heart-pounding than that series. 
 I actually liked Beatrice/Tris as a character. Yes, she has her flaws, but I enjoyed seeing her as a fully fleshed out person. Plus, she's short and small, and I can relate to that. 
 Four didn't really float my boat as a love interest. I can accept that his meanness was supposed to be helpful to Tris, but there was still a weird moment where he says that he wants to see her afraid because it makes her look "awake" and that he wants to push her until she breaks just to see how hard he has to push. Uh...not the kind of guy I want romancing me. 
 As for the plausibility of the world, I'd say that you just have to suspend your disbelief. Once you stop questioning the formation and operation of the factions, you can begin to get immersed in the story. I am, however, confused with the idea of what a Divergent is. I mean, aren't most human beings Divergent? People tend to have different characteristics and sides to their personalities, so why is it that in this future world most people are one-sided and some aren't? 
 As I said, this book was alright, but I would not recommend reading it.