1. A "bait and switch" that actually goes somewhere
With a premise of "everyone under eighteen returns to post-nuclear earth," you might expect it to quickly turn into a teen-romance free for all. We will neither confirm or deny at this time. But the hook snags you a few episodes in, at which point it ceases to matter that one of the main groups of characters are supposed to be under eighteen, or that none of those actors look like it. It quickly becomes evident that this isn't a romance-driven plot. Instead, deeper concepts with grit and complications and vigor and even contradictions saturate the characters. Much like life.
2. Flawed Characters
Disaster bringing out the best and the worst and the muddled in-betweens of human nature may be a trope, but it's a trope not done uniformly well. Another consideration is how the story and visual experience are framed to affect how you feel about the characters. The creative team behind the show have crafted believable characters who react authentically under high stress scenarios. Missing are the morally pure or unstressed characters who manage to retain the best of human nature through all the trials they face. In their place, we see adolescents and adults grappling with survival and mercy, death and love, fear and courage, and the shadow of compassion in a world where nothing is certain. And in this, the wonderfully flawed characters of the show take form, again and again and again. There is both character development and growth through the heart-clenching first four seasons. Another nuanced merit is that no one character goes unquestioned, untested, or held above others as more virtuous. By the fifth season, one can start to solidify their opinions about certain characters, but this is not to say that the some of them may not continue to surprise you. If morally objectionable decisions concern you, let it be known that dealing with the consequences is as much a part a part of the plot, and for this the show is stronger.
Don't take this lightly. When a show tries to juggle a strong plot with casting, writing, production, and effects, it is easy for something to degenerate as the show unfolds. Sometimes great actors are hampered by mediocre writing. Sometimes great writing is hampered by mediocre performances. The show moves quickly from the early teen melodrama of the first several episodes into predominately mature plots with solid performances that the viewer aback with the weight and depth of the moral choices that become part of everyday life on the renewed earth. Even when the story falters between the strife of teen romance and survival, the actors deliver the emotion with compelling youthfulness that serves as a reminder that, despite appearances, the characters are all supposed to be under eighteen and that, contrary to the judgement of adults, youth can be both more mature and just as irrational and emotional as adults. (Consider the prevalence of adult, reality-drama shows to remember how age is not a determining factor for emotional stability.)
4. Scientific Plot
While it does receive the Hollywood treatment, the science and impact of nuclear devastation as played out through the 100's exploration of the planet and run-ins with those who never left earth is the science-fiction treatment that allows us to experience the serious emotional and physical ramifications of interpersonal or societal interaction and the struggle for resources in a ravaged world. If there is a grain of scientific reality in the portrayal, it lies in the unpredictability of radiation, and the serious effects on human biology. It allows us to vicariously experience the rigor of survival, from contaminated resources to fighting for the right to territory. The mysterious grounders are forces to be reckoned with and won't be
5. Epic Scenery
The show brings us into a world where societies have survived in spite of radiation on the planet's surface. These societies are scattered across the world and developed into different cultures with their own languages, customs, dress and more. For the anthropology side and for the costume, makeup, and artistry side, the show does not shirk on creating rich scenes.
6. Raven Reyes
Raven is such a force to be reckoned with in this show that she deserves a number of her own. Raven stands out for her character growth, ingenuity, determination. Not only does she provide representation as a Latinax woman, she also provides a model for the disability community as she wears a brace on one leg to help her walk. When writerse proposed healing her leg - a TV trope where characters with physical or mental differences are restored to full form and clarity - the actress refused. She also plays a genius, combining cleverness and mechanical and computer knowledge to problem-solve. This is also a boon to have another woman unequivocally portrayed as an authority in STEM (science, technology, engineering and mathematics). She is a fighter, she is resilient, takes no shit, is unapologetically human in how she grapples with grief and pain.
Undeniably contentious - no spoilers! - but Clarke and Lexa, the first whom we know to be bisexual and with the latter whom we have a strong female-female couple, are worth the watch. Up until the circumstances in which they separate, we see two characters who at first seem strikingly different come together and discover a passion and satisfaction that is a bright joy. There is tenderness and tension, aggression and desire, selfishness and sacrifice and miscommunication and reconciliation. They are a couple worth watching the show for. And, after shows, we always have fanfiction.
A weakness of many other shows is that when characters' ambitions crash and burn they often walk away unscathed. If not entirely, then usually the fallout burns the supporting characters. The 100 trades in reputation and appeal. Characters who fumble endure actual consequencces. When they make decisions that threaten others, the drama plays out in through repercussion to alliances. Characters die, leaders are scorned, and not even the lens blur hides characters from judgement. An understated but powerful strength of the show is that it shys away from imposing glamor on these characters. When a primary character makes a difficult decision, the viewers are privy to those characters internal turmoil as well as how other characters struggle with that character's decisions.
It's post-apocalyptic, it's sci-fi. And it bridges both youth and adulthood. The characters evolve over the series, and the series also deals in the science of evolution. And between a certain two seasons, the writers even allowed the characters to age, starting the season after a few years have passed. Rather than locking them into their original concepts, they made a bold choice and the characters and plots fared better for it. It brought the ages of the characters closer to the actors appearance, it allowed for a little mystery about what transpired in the interim, and it allowed for the characterse to start further down their paths with greater capacity- or weaknesses - to face the struggles.
The top ten reason to watch The 100 is that, building on all of the previous, the regular cast includes many women and people of color. There is intersectionality - a woman of color in a position of authority, for instance - and a lack of the usual racial or ethnic typecasts, or "token representation" in which characters of diversity are given less screen time and/or not developed as characters. Culture and ethnicity may be incidental in The 100 but it is not background. For the person who is attuned to representation, there may be allegories lurking just beneath the surface. But on the whole diversity is normalized. The breakdown: fourteen or more significant female characters, inclusive of leads, supporting, and small role characters - but emphasis on significant in that they impart a substantial presence to the story. A prominent canon, bisexual female character and screen time for two lesbian couples - or from another perspective - three canon cases of bisexual representation, all with great chemistry. An Asian character who is naturally smart in more ways than archetypal brilliance.