Accidental Aesop: Respect your partner's desires in a relationship and if you can't understand them, rip the bandaid off and break up before it gets serious. John tells Lenina he wants their bond to have meaning, which is why he doesn't want to just sleep with her. She doesn't listen and keeps pressuring him. Tragedy ensues.
Accidental Innuendo: At one point, in discussing Bernard, Lenina and Fanny comment that he is "so small" (emphasis in original). Of course, in context, it is clear that they are discussing his height. To some readers, it can appear that they are talking about his length.
Are the Brave New Worlders exploiting John by parading him around like a rarity or are they showing their hospitality the only way they know how and trying to introduce him to the ways of their world? Huxley would probably argue the former. The real answer is more likely they aren't exploiting him intentionally, but John (more or less rightfully) sees it that way because of his different cultural outlook.
John's confrontation with Lenina can be read a few different ways. Is Lenina a sexual harrasser born of a culture with little concept of consent and John righteous in his refusal of her? Or is John's insistence on chastity a toxic neurosis that leads him to unjustly attack Lenina? The language he uses ("whore," "strumpet") can make the scene feel less like John is fighting off a sexual harrasser and more like he's slut-shaming and abusing Lenina. John's framing as being in opposition to the dystopia might suggest that we're intended to see him as bieng in the right, but his prior behavior—creeping into Lenina's room while she was sleeping to ogle her—casts even this into doubt.
Part of the reason John committed suicide seems to be not just that this world he has been introduced to is so horrible, but also the realization that he does not belong in it any more than he belonged in the reservation. He may have felt that there was no place where he could go and truly be himself without ridicule or pressure to conform.
For Hedonists, the Brave New World society isn't seen as bad as moralists see it. The contention there is its dystopian because the values that went into it clearly weren't written by a hedonist. But the option of going some place with no rules whatsoever if you don't like the World State's brand of it comes off as a completely acceptable option.
Darkness-Induced Audience Apathy: The sheer soul-crushing hopelessness of the story combined with the utter depravity of the Crapsack World it portrays has been known to cause severe bouts of depression in readers. In fact, the novel was chastised by critics for precisely this reason upon its initial publication in 1932.
Hard-to-Adapt Work: This book has traditionally been regarded as far more difficult to adapt than Nineteen Eighty Four and other famous dystopian novels. Not only is the book more focused on building the setting than on plot or characters, but that setting also features extreme sexuality, even between minors. An accurate adaptation would verge on vanilla pornography, if not worse. It did get two Made For TV Movies (both with large changes to plot and characters, though the 1980 UK version was slightly more faithful to the novel than the 1998 American version) and a series adaptation on NBC's Peacock streaming service (which was more of a TV drama/mini-series than an actual movie and was about as faithful to the novel as the American TV movie version [read: kept in some plot points, characters, and parts and eliminated others for censorship and artistic license]).
The worship of Henry Ford looks even sillier given the direction of his namesake company and the U.S. car industry as a whole.
The description of in-vitro fertilization years before the world's first test-tube baby was born.
Jerkass Woobie: Bernard wants so desperately to fit in with his happy, carefree society, and can't figure out why he is not happy doing the things that seem to make other men happy. He turns into somewhat of a jackass (by real world standards) once he gets a taste of popularity, but he can't entirely be faulted for trying to follow the shallow rules and values deemed important in his world.
John can qualify as well. His treatment of Lenina is rather questionable, but one can't help feel bad for all he's gone through.
Narm: Late into the book, John is wrestling with guilt over his sexual attraction towards Lenina and begins having a sexual fantasy about her. So he throws himself into a thorn bush and then beats himself with a whip. Even if you believe in chastity, this is a hillariously over the top reaction.
Squick: In the casually promiscuous society in which the book takes place, it is considered healthy - even endearing - for young children to sexually experiment with each other; if the pertinent chapter isn't the single most disgusting and horrifying thing you've ever read then there's something seriously wrong with you. There is also a memorable passage pointing out the more Freudian aspects of breastfeeding, and the descriptions of John's mother.
Values Resonance: One of the newer printings says this on the back cover, and Huxley himself constantly championed the book's increasing relevance in interviews conducted near the end of his life.
If you want further proof, just look at this◊ (illustrated version of part of the introduction to Amusing Ourselves To Death by Neil Postman, which can be read here in full).
For those that are more inclined not to view the Brave New World as villainous, the book provides an excellent speculative example of culture shock or how good intentions can lead to harm.
For Hedonists Brave New World has undergone a transition from misguided understanding of hedonism to a better alternative in comparison to the heavy moralist worldview being pushed by social reformers. Which is going to be Values Dissonance to people confused about the Blue-and-Orange Morality but Mond's points about John failing to understand a worldview that prioritizes happiness over goodness is very accurate to this debate. Sometimes somebody's Utopia is another persons Dystopia.
Mond not sending John to an island, as he requests, because he wants to see if John can survive in this utopia as an anomaly who belongs nowhere. It eventually leads to John's suicide.
John violently spurned Lenina for wanting to have sex with him without earning it; he said he wanted to win her over fairly, so their relationship would mean something. So what does she do? Seeks him out in exile with a bunch of other pleasure seekers after John has chosen self-exile. John has a whip, and a tendency to beat up anyone encroaching on his penance. He not only whips her into a quivering blob, but starts a riot among the others.
The Woobie: Poor, poor John "The Savage". As if growing up bullied and ostracized by everyone was bad enough, he ends up despising the very world he thought would be his one salvation. And after being ostracized there too and paraded around like a circus animal, he chooses exile. After the curiosity seekers chase him even there, and after betraying his beliefs in a drug-induced stupor, he is finally Driven to Suicide.
For the 2020 adaptation:
Cliché Storm: The more negative reviews of the 2020 TV series adaptation generally hold this view, as the book has inspired so many other dystopian works that the series doesn't feel like anything new.