With this book, like many, there are good and bad points to it. I gave it a 3/5 but if I could it probably would have a 2.5/5. It's probably repetitive to mention it, but like many a reviewer, I'd have to say that the world-building is not that great. I think it would've added greatly to the overall story had we been given more detail about Illea, the caste system, what lifestyles are like for each caste.
But in my opinion, the rebel aspect was even more vague than the world building. I finished the book with a feeling of not really knowing ANYTHING about them. They're from the north or south, one side seems to be looking for somthing? The other side is lethal. Those are the two points that were referenced several times, but beyond that we know nothing about why they've banded together, what caste they are largely from, what their motivation is. I mean it's one thing for there to be a little mystery...but this is just plain undeveloped story arc. The rebels are supposed to be a very real threat in the book but never come across that way. So that was weak side of the story for me.
The other thing that was a negative to me was that this story is largely focused on a love triangle. First of all, love triangles are my least favorite plot point BUT I have been known to enjoy them when they're more subtle (i.e. The Hunger Games, Partials). I like it to not be the focus of the story but an implied subplot of sorts. Something suggestive, but because there's a much bigger story going on, you aren't reading whole paragraphs and/or chapters about it. There isn't much beyond the love triangle here and for me that was difficult.
The one saving grace for me in this story was some of the inter-relationships the author created. I honestly thought she did a great job with the chemistry between America and Maxon, their interactions were fantastic. For me, chemistry between two characters has to strike just the right cord to be successful and I thought America and Maxon had that. I also liked seeing the play of their different personalities together. I also loved the friendship America had with her maids and some of the camaraderie she had with her fellow selection girls. Those were the things that kept me reading. Had the world-building been much better, and had there been anything else to focus on that was larger than just the love triangle (cause the rebels are non-entity in my eyes) I would have rated this a 3.5 maybe a 4. It's a little disappointing seeing promise in a book but not seeing it realized.