Paradox having a sister wasn't really hinted at at all in the first season, and actually runs somewhat counter to the back-story they gave her. Depending how charitable you're feeling, this is either her being an Unreliable Narrator or the new writers inserting something they just came up with. Fans of the original series are likely to be more forgiving, though, knowing the "Gemini = Twins" thing.
The Gemini Saints curse, which consists on all of them being fated to fight against their own twins. And the fact that Paradox and Integra are the ones who finally broke said curse (in the same episode where this concept was established, for crying out loud!). Not only this idea came out of nowhere, it doesn't even make sense: If that was the case, Saga and Kanon would have already broke the curse by teaming up in the Hades arc, and fight for Athena.
The opening is a nice sendback to the original opening, which too was pretty awesome. The song starts off nice and sombre complete with a female singer (Shoko Nakagawa of "Ray of Light" fame, who also voices Saori in this series), then kicks off into a rock off similar to the original, even going as far as bringing the original singer for the song into the song.
There's also the second opening, Root Five's "Next Generation" (also called "New Ω Myth", though that doesn't seem to be an official title), which, as a rock/techno take on Seiya themes, manages to trade off a notch of bishonen for a notch of badass while still remaining surprisingly faithful to the concept.
Stardust Chant, the song that plays during episode 87 when Cataclysm Slash and the Athena Exclamation clash against each other.
Broken Base: Season 2 as a whole. Is it better that the first season for returning the Cloths back to its classic roots, bringing back the old cast and have them join forces with the new one, or is it a Seasonal Rot for swapping out key staff members for relative unknowns and Pandering to the Base by bringing back the clunky and old-fashioned Cloth Boxes and hindering the Character Development of some characters, like Souma and Yuna, in favor of the return of the classic Saints?
Contested Sequel: Much like with Dragon Ball GT, it's gotten this reception, due to Kurumada's near-zero involvement. While it does avert the filler that plagued the original due to it being an anime original, and the series does improve as noted below, the early episodes, changes to the cloths and art style are often cited against it.
Taurus Harbinger for his anti-hero traits as well his long story arc in contrast to previous Taurus Saints whose actions were quite disappointing.
Libra Genbu is one of the better received Gold Saints and many were sad when he died.
Titan is also coming across as one of the most developed villains from the franchise and his duel with Seiya made him more popular. Many wished for him to have a happy ending with Pallas, which he eventually got, Walking the Earth with her.
Saint Seiya GT, both made by Toei Animation, with no input from their original creators, set many years after the original series' ending, not canon to the original universe and with polarizing fan reactions.
Saint Seiya GX, both spin-offs of a popular anime, focusing on a younger cast, introducing a controversial school that teaches each universe's concepts, and also with polarizing fan reactions.
Abzu after being removed from Koga. His armor is an asymmetric amalgamation of animal heads, black armor, spikes, and much, much more. Considering that he's a primordial god who birthed life, it's kind of justified.
Europa, who's designers were aparently intent on creating a character that looked like a colorful, asymmetric clown.◊
Germans Love David Hasselhoff: Like the original series, Saint Seiya Omega is very well loved in Mexico, so much so that the licensors managed to bring back all of the main cast when dubbing Omega, including the singer of the Mexican dubbed opening!
Growing the Beard: Despite the slow beginning, the show's first episodes are relatively light-hearted as they focus on Koga meeting the other main characters and learning how to use his Cosmos. It is when Koga is beaten up by the Director, Mars returns and the main characters start running for their lives that the show starts showing its true colors.
The Director's betrayal seems harsher if you remember Capricorn Saints are said to be the most loyals to Athena... Oops.
Only in the anime. In the manga, no such thing is ever stated and Shura is a traitor being damn well aware of it and taking pleasure from having killed Aiolos.
In the Brazilian dub, Ryuhou's first spoken line, said to Kouga as he's about to leave Palaestra, is translated as "It's too soon [for you] to leave." With his local voice actor's sudden death at the age of 27, this line has become all the more eerie and even a little prophetic.
Paradox' strongest move is called Final Destination. The premise of that film is that people tried to cheat their fate (specifically, their death) but fails gruesomely, and no matter what they do, they can't fight fate. Paradox always cheated her fate by predicting her future through reading the stars, then chooses the easier option. By the time she stopped cheating, death comes for her. Sure, she managed to defy the fate of Geminis, twins who are supposed to hate and kill each other, but she cannot avoid the fate of the older Gemini would die before the younger does. Subverted in that she is completely aware that continuing to fight when she is mortally wounded would kill her. Doesn't change the fact that in the end, she cannot defy fate completely.
Several fans already predicted Eden's role in the second season during its premiere. It also helped that the opening basically showed people Eden's side.
Shiryu using the Libra Cloth was shown in #77 preview. Many fans knew it would show up after he gave Dragon Cloth to his son and Genbu died.
Iron Woobie: Eden. He's the only member of the main cast to have entered the series with all of his loved ones alive and well. Sadly, this doesn't last. First, his father murders Aria, the girl he loved, before his very eyes. His half-sister, whom he truly cared for and admired, dies after losing control of the Scorpio Gold Cloth. His father dies the instant that Eden finally convinces him of his wrongdoings. His mother is killed right before his eyes when she sacrifices herself in order to keep Abzu's attack from killing him. He pretty much loses everyone he ever cared about in the span of twenty-four hours. He only really looses his composure once, though.
It Was His Sled: Subaru's identity. The openings don't even try to hide it.
Memetic Molester: Gemini Paradox and Pisces Amor, due to their crush on the underaged crushes (Ryuuho and Yuna, respectively).
Misblamed: Some fans of Lost Canvas blame Omega for Lost Canvas not getting continued, despite a weekly television series has absolutely no effect on what is an OVA release, and that the two shows are done by entirely different animation studios.
Moral Event Horizon: Medea has committed or been responsible for a great number of evil deeds. However, our first real taste of how deep the rabbit hole went was when she callously sacrificed her Love Martyr stepdaughter Sonia, sending her out with a Gold Cloth she could barely handle to die in battle and slightly slow down the advancing Bronze Saints.
Mars (the god)'s Evil Plan in episode 29 to move Mars (the planet) between Earh and the Sun and thus blot out the Earth's sunlight puts one in mind of a certain other Martian: "It obstructs our view of Venus!"
About 22 minutes into episode 34, Koga is unleashing his dark Cosmo and lets out an angry yell. However, this yell is so brief, random, and abrupt that it can incite laughter rather than a feeling of suspense.
The whole episode about the 10-Minute Retirement of Haruto to become a rock star was intended to be something very serious and dramatic, but some viewers found it to be unintentionally amusing. There is also the scene which shows why Haruto decides to become a singer after listening a song in the radio (which is the new opening of the series.) What makes the scene so bizarre is that he was listening rock music in the radio seated next to the grave of his friend (and previous Wolf Saint) Yoshitomi. Haruto announces his 10-Minute Retirement to become a singer with this magnificent line:
Haruto: I am no longer a servant of Athena. I am a servant of rock!
The way everyone pronounces Saturn, which sounds like Sataaaun, in a clear attempt to avoid sounding like Satan, which is pronounced very similarly to Saturn in Japanese.
Narm Charm: In the Latin-American Spanish dub, Harbinger's first voice actor was Juan Alfonso Carralero, known as the semi-official VA for Paul Zaloom, Will Smith, David Hasselhoff. Older fans familiar with the guy's work couldn't help giggling upon hearing Harbinger talk like an angrier Agent J or Mitch Buchannon, yet at the same time they couldn't help thinking "so THAT is how Beakman sounds when he's truly angry?! Wow, cool!"
Pisces Amor, the most powerful of all Gold Saints by a mile and Medea's brother, has an infatuation with Yuna. While not quite played to Yandere levels, his persistent advances (to the point of willingly forcing her to sit next to him using his powers) still come off as quite unsettling.
Virgo Fudou is one distubing saint. His palace was very unsettling with that magma that drains life energy but that's not all. When he dons his cloth and lauches his attack, Nightmare Face kicks in and boy is it creepy (though to be expected with the name Fudou).
Abzu himself and Koga tapping into his Darkness element from #49 - 50.
Pandering to the Base: Season 2 as a whole. Virtually every new theme introduced in season 1 such as clothstones and table-based elemental powers was completely thrown out in favor of reverting to familiar themes and plots used in the past, many of which had already been frequently recycled in other spinoff productions.
Replacement Scrappy: Gemini Paradox is considered this in some parts of the fandom, either because of her It's All About Me attitude, her Memetic Molester behavior towards Ryuho, or simply because she's not fan favorites Saga or Kanon.
Tatsumi was hated by most of the fandom during the original series for his scenes involving beating kids, going as far as to whipping Ikki and never getting punished for it. Now, in Omega he is much of a Plucky Comic Relief and at the same time Older and Wiser. Unlike Seiya, Koga considers him an important person comparing him with a relative. This was proved in the third season's beginning when he defended Koga from an enemy.
While not a real Scrappy, Seiya was the least popular Bronze Saint from the original manga. Some fans didn't like his Hot-Blooded personality, his Idiot Hero persona, or how much damage he could take. In Omega Seiya is instead characterized as Older and Wiser acting as The Mentor without stealing the credit. He was so popular he made it first to the Toei popularity poll from the series. His Big Damn Heroes moments probably helped.
Saori/Athena is infamous for being a Damsel Scrappy. While the early episodes didn't help to deny this, late season 1 shows a scene where she manages to hold a meteor falling to Earth. While that moment lasted shortly, in season 2 she actually goes with the Saints to enemy's place in order to confront her sister. The fact that she manages to fight against Pallas with her God Cloth and winning all alone made the episode noteworthy.
The Steel Saints were absolutely hated in the classic series due to being created for the anime, causing them to appear awkwardly in scenes they weren't meant to be in, clearly existing only to sell toys, and then they disappeared mysteriously; in Omega they are shown to serve as the Cannon Fodder of Athena's troops, they hardly take any spotlight as they exist to get shot down, and whenever a Steel Saint is focused on (Ema, Keri), they're well-written and likable. Not being constrained by being a manga adaptation allowed far greater use of this concept. Subaru deserves a mention here, as at first he is annoying at first, but several episodes later made him character more likeable.
Take That, Scrappy!: Two minutes after his return in the series' second season Haruto beats up newcomer Subaru.
They Wasted a Perfectly Good Character: They could have shown Aria developing into a successor for Saori, paralelling Koga's development as Seiya's successor. Instead, she gets killed halfway through the first season.
In the second season, Libra Genbu and Equulus Celeris.
Visual Effects of Awesome: The second season's finale features Koga and Abzu in one of the most mindblowing fights scene the franchise ever saw. This writer got Tengen Toppa Gurren Lagann vibes when Kouga had no colors.
What Do You Mean, It's Not Political?: One can't help but see Yuna as a character with strong feminist bent, with her defying the traditions for female saints to wear masks. The same defiance can also be seen as a Take That! against certain religions with similarly imposing decency law. The significance of this is somewhat weakened when taking into account the series' long history of characters openly ignoring the mask law when previously defied, such as Ophiucus Shaina or Chameleon June.
Win Back the Crowd: Or to be more specific win back the Broken Base. People who nitpicked the series just based on the Cloths started becoming nicer with the second season's new designs.
(also called "New Ω Myth", though that doesn't seem to be an official title), which, as a rock/techno take on Seiya themes, manages to trade off a notch of bishonen for a notch of badass while still remaining surprisingly faithful to the concept.
