I'd seen this listed as dystopian, but it doesn't really feel like it coming out of the gate. The world suffered some apocalypse in the past and the city of Chicago has rebuilt itself on the foundation of five factions based on personality traits/ideals that were selected by the people of the time as ways to combat the evils present in humanity. Citizens are allowed, once only, to choose to which faction they will belong. This feels like it was set up as Utopian, however Roth applies the realistic quality of imperfect people. Ultimately people are flawed and some small portion of them will seek to bend the system to their own empowerment. I also enjoyed the sense of agency left to Tris. She has her own goals, conflicts, and choices and lives with their consequences. Even when a love interest enters the picture, it is kept as a second-tier to the primary focus Tris' main goals. Overall I enjoyed this book and am looking forward to the rest of the series, despite hearing that the third book can be ... polarizing. 
 SPOILERS BELOW 
 I really only have a couple of complaints, and one of them revolves around the factions and citizens' ability to choose one once during their lives. It's not that I'm bothered by this as a framework for a fictional attempt at Utopia, it's more that this seems to be our world, and in our world people have free will. They may chose to blindly follow something, but ultimately they all have the same basic choices. This plays into the central conceit behind Beatrice's Divergence. The book seems to imply there is something biologically different about Divergents that make them more flexible. The resistance to drugs makes sense from a biological perspective, but the implication that this resistance is tied to their Divergence and ability to choose doesn't strike me as realistic. 
 I also felt that the end conflict was a little forced, mainly in the self-sacrifice of (view spoiler)[ her parents. I agree it is consistent with their personalities and lifestyles as Abnegation, (hide spoiler)] but it feels a little sudden and not well setup.