These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
The above article makes some interesting points, but largely glosses over the fact that Ender is a pre-pubescent child throughout the original novel. For all his intelligence and maturity, he's still just a kid and, unlike Bean, unaware of the full context of his actions until it's too late. Not only that, he wasn't given enough information to even be able to comprehend the consequences of his actions. He was lied to, and didn't know that he was actually commanding real men in a real war. He was so disgusted with himself that he went into a comatose state for a few days, at least, and spent the next 3000 years trying to repent. He abhorred violence, despite the fact that he was very good at it, and was also devastated after his fight with Bonzo. The later revelation that aliens had been dissecting his dreams and trying to enter his mind for weeks leading up to the big moment, and that the military officers running the show did everything in their power to hide the truth from the kids for the specific reason that they needed the little tactical geniuses to never hesitate over loss of life (Human or Formic) during a battle (the officers claim that key battles were lost during the previous wars when commanders hesitated to order soldiers to their deaths, because the Formicsdon't). The article also makes it sound like "to be a killer, you must know you are killing" is a bad thing, even though it's what most people would think anyways. The claims that we never get a chance to find out the motives of Bernard, Stilson, Peter, etc. only Ender's, is somewhat moot when you remember that in all of his acts of violence Ender was acting in self-defence, while those bullying him were attacking out of jealousy. The claims that Ender committed genocide is highly suspect when you remember that the buggers are a hive-mind, meaning most of them aren't even sentient, so at worst it was large-scale animal cruelty, at best Ender caused a power outage. So yeah, Ender kinda is a victim.
Oddly enough, this debate takes place inside the story's canon. Ender, the poor kid who saved the world, or Ender the Xenocide? It goes both ways depending on where you are in the timeline and how the Formics are perceived—which, itself, is a plot point.
The point of the article is that the plot is a series of incredibly contrived circumstances where Ender can commit what, to the reader at least, feel like sublimely satisfying revenge murders, and yet always somehow walk away looking like a plaster saint because he's innocent on a technicality (even if that technicality is just that "he didn't enjoy it," or "he only meant to cripple them," or "he didn't hang around to watch the children he'd beaten to death actually die"). In-story, Ender feels guilty, but we the readers get to simultaneously enjoy a couple of savage murders, and then get the added bonus of feeling indignant that Ender would even blame himself for deaths that are clearly never, ever his fault. It's the ultimate revenge fantasy, getting to beat your persecutors mercilessly to death with your bare hands, and yet be magically blameless for the deed. The article argues that this is not a good fantasy to indulge in.
Complicating the matter with Ender's killing of Bonzo and the first bully (who are the only people Ender killed directly), Ender would use excessive force in attacking them and (in the case of the first bully) kept beating them after he'd already won. At the same time, there was no intent to kill either of them, only badly hurt them, which makes the question of Ender's guilt in those issues much blurrier.
Harsher in Hindsight: The book says that the French, in their "arrogant separatism", refuse to teach Standard (English) to their kids until they're older than is ideal. Nowadays, a large percentage of French people speak English and/or some other non-French language. Meanwhile, there are huge controversies in America, the author's country, over teaching non-English languages to children.
Hilarious in Hindsight: Blogging being Serious Business in Ender's Game, enough to cause international tension. Hilarious because if politicians took half of actual political blogs seriously these days, we'd probably have had World War III by now.
Even better: a Memetic Mutationgoing viral and managing to save lives. When Petra is in Russian captivity after returning to Earth, she creates a little dragon graphic with a code hidden inside, trusting that it will somehow get to Bean and he'll decode it. It works—she spawns a massive flow of dragon-related memes, Bean recognizes the connection with Ender's Dragon Army, and voila! Big Damn Heroes. Except, of course, Achilles has something of a plan going on...
The rather nuanced morality of the book is rather hilariously in contrast with Orson's extremely black and white views on politics and LGBT topics, culminating in his recent rewriting of Hamlet with gay demons.
Ho Yay: Hilariously, considering the politics of the author, but the book is chock-full of homo eroticism. Part of the book takes place on planet Eros, the relationship between the boys in the school is something akin to the homosexual ones between Greco-Roman cadets, Ender refers to Bonzo as being beautiful, Alai has what is very strongly implied to be a gay crush on Ender, oh - and the boys sleep together and wrestle buck-ass naked for most of the story.
It Was His Sled: At this point, it's very hard to avoid spoilers of the ending.
Magnum Opus Dissonance: Originally, Ender's Game was just another short story that Card wrote to pay the bills. He only expanded it into a novel so that it could serve as an introduction to Speaker for the Dead (the story that he really wanted to tell). While Speaker is certainly well-regarded among sci-fi aficionados, Ender's Game has become one of the most widely read sci-fi novels of all time, and it's now required reading in many middle schools.
Mis-blamed: Ender's Shadow is sometimes blamed for giving some of Ender's accomplishments to Bean to as to make him look smarter. All of Bean's actions there (gaining the deadline, leading Dragon Army in the final battle, saying the joke that gives Ender his epiphany) are in Ender's Game. Only two are semi-retcons; the kid who takes the brunt of the assault in the first battle wasn't named, and Ender himself notes someone may have given him a great army, though he assumes a teacher organized it.
Nightmare Fuel: Ender's sessions in the mind game are horrific. First, he kills the giant by clawing its eye out and digging into its brain. Then, there are the werewolf children that brutally murder Ender's avatar until he kills them. And then the end of the world...
One-Scene Wonder: Though Achilles is present throughout most of the Shadow series, there is exactly one chapter from his point of view. HOLY COW.
Spoiled by the Format: If you're paying attention to how many pages are left at the end of the book, you know that the Command School "simulation" has to be the real thing... because there isn't enough time left in the book to do it all over again.
Averted in the digital (iTunes) version. They placed a preview for another book at the end, so you finished the story while still believing there were many more pages to go.
In Ender's Shadow, Bean, being the only one who knows what's really going on and knowing all his men are going to die in the final battle, quotes 2 Samuel 19:1. "O my son Absalom. My son, my son Absalom. Would God I could die for thee, O Absalom, my son. My sons!"
Unfortunate Implications: Humanity is fighting the "buggers," and the word is used as an insult among humans throughout the book. In the Shadow series, they're referred to more often by their official name "the Formics", though some still call them buggers as an insult. May be unintentional—"bugger" isn't a widely known homophobic slur in the U.S.—but Card's public stance on gay issues inevitably begs the question.
It's Short, so It Sucks : Primarily for fans of the book - those that hadn't read it seem largely satisfied with the result, while those that had wish it was longer than the 1 hour, 45 minute runtime for 300+ pages of source material.
The reviews often attribute positives like the ethnic diversity of the cast and non-pejorative name "Formics" to the film, while blaming Card for negatives like the name "Buggers". Both positive aspects come from Card's books too.
Narm: It can seem kinda unbelievable that Bonzo is really a threat to Ender's life in the showers, since he's so much shorter than him. It doesn't help that his actor also played Rico in Hannah Montana, which can kill any atmosphere the film's trying to build.
This is mitigated in that, while Bonzo is a good few inches shorter than Ender, he has a lot more muscle mass, like a 14 or 15-year-old going up against a wiry 10-year-old. Plus, this isn't the only time a Disney Channel actor played a terrifying psycho.
The last Hive Queen who gives Ender the cocoon. Nothing can be said between them, but their peaceful contact is enough to let them trust each other.
Overshadowed By Controversy: Card's negative stance on homosexuality has tainted the film's publicity, enough that it got noted on Wikipedia. It's since sparked much debate about whether one should separate an artist from their work, or if merely paying for it is a vote for their ideology. Unusually for an adaptation like this, the first trailer does not mention Card except for a very tiny credit in the mass credit roll at the very end. The people behind the film have also naturally made a massive effort to distance themselves from Card, saying that it's just a sci-fi story that in and of itself doesn't indicate anything about homosexuality.
They Changed It, Now It Sucks: From what was revealed in the trailers, plenty of complaints arose that the candidates are too old, that Mazer Rackham's battle was at Jupiter instead of Earth, that Ender's training at the Battle School is too short, etc. This, of course, escalated with the movie itself, which cut other elements like Valentine and Peter's side-plot, most of Dragon Army's career, most of Ender's jeesh, and the epilogue where Ender writes his book The Hive Queen.
On top of this is that, due to time constraints, characterization was dropped in favor of getting the critical details inserted appropriately. It also violates Show, Don't Tell (ironically, given the medium) by having Ender mention that Command School had been going on for months, where he and his team were going at it every day - so Petra's Heroic BSOD in the middle of one fight is completely omitted, and Ender's reaction at the final simulation was vastly different than in the book.note In the novel, it's portrayed as him getting fed up with the vindictive cruelty he sees from the adults in forcing them into a hopeless fight, and wanting to do something so repugnant in the simulation that he'd get kicked out. In the movie, he cheered alongside his jeesh for overcoming impossible odds in the simulation