Things I liked:1. the characterizations of factions and the little things that made them distinct. It was fun to wonder which faction I would best belong to (Erudite, if not evil) versus which faction I would want to belong to (Dauntless, if I weren't so afraid most of the time).2. Tris. Even though she struggles some from the lame YA heroine tendencies (a lack of a basic understanding of romance, a blatant inability to understand the obvious), she was pretty badass. I liked the growth she showed and the realizations she made about herself. She was relatable but not overly pathetic.3. a degree of moral ambiguity. Sure, the bad guys seemed so obviously evil it was almost Candoresque forthrightness, but the good guys had layers. Tris herself; her friend Christina was a good pal but not always the best; Al, the big softy with a dark side; Tris's father, who pushed the pursuit of selflessness too far. I like it when things aren't black and white. Candor is so not me.4. the trials of the Dauntless initiates. I liked hearing about their training and seeing the slow build-up. That said, see 2 and 4 below.Things I didn't like:1. romance. mostly because in dystopian YA novels it seems like authors think it's obligatory to have a romance. It isn't. And if you want to have one and you're planning a trilogy, you can always have it develop more slowly (as most do in real life) by spreading it across the books1.6 also on the romance - this is so superficial but I actually couldn't find any attraction to Four, ahem, Tobias, once we learned his real name. I mean, Tobias? TOBIAS??? 2. too much action crammed in last 50 pages. Although I read it quickly, this book was loooong. It needed some editing to cut unnecessary bits and needed better pacing. 3. lack of description on the dystopian world. Whywhywhy is Chicago like this? Why is beautiful Lake Michigan a marsh and why is the Bean rusting? How is this world being held together? (I don't buy that the factions are just peaceful because it's the best way.) What is it like outside Chicagoland? Maybe these questions will be answered in the subsequent novels, but their omission struck me as vaguely lazy. 4. the trials of the Dauntless initiates. Ok, so I liked/hated them. They were interesting to a point, a very fine point that the author went about 1000 lightyears across. I only needed to read about fear simulations a few times and then they were snoozy. Repetition of this was boring; I would've preferred reading about more varied trials.OVERALL: I enjoyed it. It didn't make me think much and it had a lot of flaws, but I'm already impatient to read the sequel, Insurgent.