In retrospect, I shouldn't have read this book. I don't typically like YA, I don't particularly enjoy fluff, I strongly dislike romance, and I'm impatient with fluffy YA romances masquerading as gritty dystopians. It all started when I saw the second half of a "The 100" episode while at the gym, and there seemed to be all sorts of interesting plot lines that I utterly failed to grasp, not the least of which was what the 100 was actually a 100 of. While in retrospect, I realize I should have just looked it up on Wikipedia, I was momentarily out of books, The 100 was available in my library, and I was feeling curious. Plus, I assumed that a title as blatantly concrete as "The 100" must have a clever, punny, double-entendre-esque meaning. (It doesn't, by the way.) All of which forced me, inevitably, to a future in which I would waste an hour and a half of my life reading the book, and waste 15 minutes of my life writing a review to pan it. 
 So anyway, if you enjoyed this book, please ignore this review. If you plan to read this book, please ignore this review. If you're pretty sure you'll never read or enjoy this book, well, I read the book so you wouldn't have to. (You're welcome.) All of which is to say that this review is likely to contain spoilers, and since there isn't much plot in the book in the first place, I'm not entirely sure what consists of a spoiler and therefore cannot mark them appropriately. 
 The 100 is simply one of the hundreds of YA books out there that consist of highschool rebellion and romance superficially wrapped in a vaguely interesting but utterly ill-conceived dystopian backdrop. In this case, said dystopian backdrop is a world destroyed about three centuries before via some sort of nuclear apocalypse, with the only remnant of humanity hanging out on a space station revolving around the ruined earth. Said space station utilizes capital punishment as the penalty for all sorts of minor misdemeanors. Underage offenders are instead imprisoned until they turn eighteen, at which point they are retried and inevitably found guilty and penalized with capital punishment. As Morgan tells us, since the incident that destroyed the earth, the space station decided it must maintain a stable population, and thus reproduction is strictly policed and each couple is allowed at most one child. Clearly Morgan is unfamiliar with the elementary basics of mathematics, and perhaps since much of her plot revolves around the idea that siblings are an alien concept, none of her beta readers or editors were able to correct her misapprehension. To keep a stable population, you need each couple to have, on average, two children. (Actually, you need the average to be slightly more than two, due to non-child-bearing members of the population, accidents, child mortality, capital punishment for minor crimes, etc.) 
 With a population restriction of one child per couple, each generation's population will be decreased by 50%. The space station has been up for about 300 years, which corresponds to approximately 15 generations. If the generation gap is 20 years, P0 is the initial population, and P(t) is the number of people in the t-th generation, then we can estimate the generation size at time t as P(t) = P0*2^(-t/20). If you want a visual, the population per generation, starting with 10 million people in the first generation, would look like this: 
 This means that to even have 100 kids left in Clarke's generation to throw out of the ship--and this assumes 100% of the kids of her generation are delinquents-- they must have started with over 3 million people in the first generation. 
 Speaking of capital punishment, another aspect that struck me as impressively idiotic was the way the ship actually implemented its one-child policy. One would imagine that the station would have a forced birth control policy--or even sterilization for the post-one-kid folks. Nope. They apparently require abstinence, and even an unplanned pregnancy is punishable by death. We have one instance of teenage pregnancy--both father and mother are supposed to be killed because they were fooling around. Has anyone in this world heard of prevention, or is that expecting too much from a YA book? 
 Not that anything else about the worldbuilding or setup makes much more sense. It's never clear precisely how many people are onboard--I actually think Morgan carefully avoided defining this, as the impressions she gives vary wildly depending on the scene--but somehow it's enough to create several different communities with wildly different cultures that apparently don't intersect. One of them is the "wealthy" set; the others are the impoverished ones. While children of the "wealthy" community work and do whatever they want, the poor community kids do whatever their parents did. Because it definitely makes sense when your talent pool is that limited and you appear to have a semi-socialist setup to create huge social divisions and follow completely different career models in different areas. 
 The characters don't make much more sense either. My favourite case of complete idiot irrationality (view spoiler)[--well, possibly second favourite; the Darwin Award definitely goes to Wells for destroying the ship's airlock in the effort to get the girl he loves put without any support on a radioactive and possibly unsurvivable planet, although why no one in the last 300 years put any effort into either fixing the ship or developing gear to explore the planet utterly baffles me. Or Octavia, for stealing all the drugs, dooming everyone in the colony, and thinking she could get some sort of high off penicillin and the like, coz apparently all drugs are the same, amiright? Or Clarke, for silently accepting her parents' murder spree. Or Glass, for existing. Actually, choosing the dumbest, most illogical character in this book is really, really hard-- (hide spoiler)] comes from Bellamy, who holds the chancellor at gunpoint to get onboard so he can protect his sister. And what does protecting his sister entail? Well, since he committed a crime and is therefore a wanted man, "protecting" his sister means forcing her to leave the rest of the 100 with him and, presumably, live a life of danger, isolation, and loneliness, away from any assistance or community that the rest of the kids might have provided. And throughout the book, everyone keeps speaking of Bellamy's kindness and lack of selfishness without the requisite sarcasm. 
 Meh, I'm not going to waste any more time on this. Long story short, the book is a thinly-imagined dystopian wrapping over a lot of teen angst and romancing. The focus of the story itself is on the teens and their loves and their friendships rather than, I don't know, their struggles to survive on a now-alien world. The story switches perspectives often and utilizes flashbacks repeatedly and gracelessly. Every so often, I encounter a YA book that imbues me with a certain amount of enthusiasm for the genre. This is emphatically not one of those times.