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 Chimera Ant arc ran for more than 7 years, thanks to it having long breaks on top of lasting 132 chapters. This arc has been much better received in the 2011 anime due to the long breaks not existing...but even then, the arc has taken over a year to complete, and has yet to reach its climax. In addition, by the time it gets to the palace invasion, you're at the hands of a narrator doing the work of Captain Obvious which slows the story for some viewers.
The Hunter Exam in the original anime where portions of the arc was extended with Filler.
Killua in the first anime is given a more mature look, including slanted eyes, a more older looking face, and noticeably taller build than fellow 12-year-old Gon; in the 2011 reboot, Killua is given a more "cute and younger" design, with large and round expressive eyes, a height deduction, slimmer build, and age equivalent face. Just◊ look◊.
Actually, both anime renditions make the entire series more attractive, as in the manga, the art was often drawn lazily with a lack of detail, especially to the characters and scenery with very few things actually having detail. Shownhere◊ for◊ a◊ few◊ examples. Why the manga-ka chose to have so much emphasis on the turkey in the last one is a mystery.
Angst? What Angst?: Gon. His father abandoned him to be a Hunter, never once contacting him or checking in on him afterwards. His response? Try to become a Hunter to find out just how great it is that you would be willing to abandon your only son. He also isn't upset about most things. The first anime subverts this by giving posttraumatic reactions after receiving pity from Hisoka in the exam.
Finally subverted in the Chimera Ant arc, where he goes through a severe Break the Cutie situation when his mentor is killed by an Ax-Crazy cat ant. He becomes infuriated with the latter's sudden show of empathy to an insult to his simple world view, and the Awful Truth that his mentor who's long been dead finally drives him down the Despair Event Horizon/
The Tower of Heaven arc usually gets this for wasted potential beyond being just a training arc for Gon and Killua to learn the basics of nen. Throughout the arc, there is legitimate build-up to fighting possible "tower-heads" if one was to rise high enough in the tower...and yet Gon and Killua never get a shot to fight at least one of these leaders and basically called it quits after Gon's fight with Hisoka.
The Genei Ryodan arc was noted by many to have one of the most disappointing endings in the series due to almost all fights being cut short and others showed offscreen and some wonder if the author actually plans to make it continue in some time.
Are disappointed or don't mind that it's a reboot.
Are disappointed that the new series doesn't change things aroundnote Including things like anime-only characterizations, such as Killua's moodiness like the previous one did or don't mind that it's truer to the manga.
Lately each major arc seems to do this. Greed Island got really long winded and overly complex, but had some redeeming qualities shine through; and opinions are REALLY divided on the Chimera Ant arc. Some declare it the complete and utter ruination of the series, while others find it to have the depth and complexity that makes Hunter x Hunter stand out among Shonen.
The opening theme from the reboot has been used for all episodes regardless of the arc. You either love it or hate it. The former also started growing tired of it.
The narration throughout the palace invasion portion of the Chimera Ant arc gets this in both the manga, and the 2011 anime adaptation. You either enjoy it, because it brings a different approach to portraying how the battles go down, or you find it annoying, and just wish it did the battles in normal Shonen fashion.
Crowning Music of Awesome: The original TV series has a great, fitting soundtrack. Some of the theme songs aren't too shabby as well!
Cult Classic: The original anime and manga had such a strong following that it got a revamp by MADHOUSE in 2011.
Designated Hero: Lampshaded a lot. While in the Chimera arc, the King will allow several humans to survive, the Hunter Association wish the Chimera's complete extermination. It goes so far that even Gon could be a Designated Hero. His desire for revenge goes so far that he threatens the Chimera with killing the innocent Komugi.
Die for Our Ship / The Scrappy: While most of the characters are likable, fans genuinely agree that Pouf is an incarnate of the Ron the Death Eater trope, as he tried to have Komugi, the one who was causing Meryem to act kinder, killed and his Large Ham obsession with the king that go on for pages are very long winded, long story short: he is the least liked of the Royal Guards.
Ensemble Darkhorse: While initial opinions about Pariston were mixed, his neverending manipulations and the revelation of his true intentions made him stand out within the readers (even more than Gon's father!)
"Octobro" for Ikalgo has become popular after his appearance in the 2011 anime.
Foe Yay: Hisoka towards Gon and Killua, and also towards Chrollo.
Illumi towards Killua & possibly Alluka.
Growing the Beard: The later parts of the Hunter Exam arc. And the Phantom Troupe arc takes this full throttle.
God-Mode Sue: The Chimera Art King. Probably the series' most powerful character born with the best traits of everything the Queen consumed. None of Netero's attacks manage to inflict notable damage and he leaves Netero nearly dead with few movements. In the end it takes Netero's Kamikaze Attack through a rose bomb to kill him.
Memetic Mutation: Gon's Nen-powered adult form seems to have become this in Japan as Gon-san, thanks to his very odd hairdo and serious, stoic expression on such a cheerful character.
Moral Event Horizon: Several times, at least once for every villain. The Genei Ryodan are a very interesting example, as they start out on the other side of the Horizon and then slowly inch back as we learn more and more about them and the environment they came from. Then we learn what actually went down during the Kuruta massacre, which likely vaulted them back over the horizon for some readers.
Meryem constantly dances a fancy jig around this line.
Nightmare Retardant: While the series is noted for it's brutality especially compared to other shonens, the impact of some scenes can really be lost by the crappy art work.
The original anime adaptation; most of the Filler material wasn't well liked by the fan-base.
The 2011 anime version; the early censorship throughout the Hunter Exam arc got a lot of flack for this. Episode 76 in particular got a lot of backlash due to the changes made to Gon and Kite's past relationship.
They Wasted a Perfectly Good Character: Kite. He could have stayed in Gon's group and fill Leorio or Kurapica's spot. Instead, he is horribly murdered by the Chimeras and his death is used to give Gon angst (and thus Killua) for the entire Chimera arc.
Plus Kurapika, Senritsu, and others. It's a standard Togashism.
Special mention goes to Killua's younger siblings Alluka and Kalluto. I think his mom REALLY wanted a daughter after 3-4 sons in a row. It would explain why Kalluto's by her side dressed in a kimono and looking about as feminine as feminine gets. Alluka is an especially strange case; Killua refers to Alluka as female, while Illumi refers to Alluka as male.
Even Illumi gets this sometimes. The biggest example was how in the South America he was voiced by a woman.
Wangst: Killua in the Chimera arc gets... too sad by Gon's decisions to do things alone.
What Do You Mean, It's for Kids?: Even by Japanese standards, the manga (especially), and both anime series are considerably violent, especially during the Chimera Ant arc in the manga. Nonetheless, the story was intended for family reading/viewing.note Especially the Nippon Animation (of World Masterpiece Theater fame) version from 1999-2001, which tones down certain parts of the story.
Its worth noting that the English version of the manga is published under the Shonen Jump Advanced label for older readers. Something not even done with its predecessor, YuYu Hakusho.
During the latter half of the Chimera Ant arc, the reboot of the anime was moved to a later time slot.