A wonderful book.A bit depressing at times, but a nice story nonetheless.I didn't give it five full stars because there are some questions left unanswered:- why the trains don't stop and the Dauntless have to jump on/off them while they are moving? And to what purpose do the trains move, if they never stop and therefore the only people able to use them are the Dauntless?- why the Dauntless can't distinguish between bravery and foolishness? Sometimes they don't seem to recognize actual bravery when they have it under their noses, and that's a bit hard to believe from people whose lives are built upon the concept of courage.- who cooks the food in the Dauntless compound? (and for that matter, who produces the food?) And who does the cleaning? And the laundry? And how does the air exchange work? The compound looks like it's running all by itself.- on that note: all this fictional world looks like it's running all by itself. I mean, it's my understanding that all the factions do jobs that more or less pertain to the tertiary sector of the economy. Who produces things?- who takes care of the many injuries the Dauntless get during their jobs (or their training)? It's said that sometimes they go to an Erudite hospital, but I wonder what do they do when they need a doctor for something that doesn't need actual hospitalization.I had many more questions while reading the book, but I didn't take notes and these are the ones that I now remember off the top of my hat. However, don't let these question marks stop you if you are pondering about reading this book or not: read it. My punctiliousness aside, it's a good read.