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.
Anti-Climax Boss: None other than Hades himself. He doesn't do anything but take a hit.
Ass Pull: Regulus being able to perform both the Athena Exclamation (which requires three Gold Saints) and the Zodiac Exclamation (a move that's more powerful than the aforementioned Athena Exclamation and which requires all twelve Gold Saints to pull off) all on his own during his battle against Rhadamanthys.
Awesome Ego: Cancer Manigoldo and Gemini Aspros both have huge egos (Aspros' definitely shows right before and during his battle against Mephistopheles Yoma/Kairos) and they are indeed very much awesome.
The Gold Saints were this in the original series and one of the main reasons why they're the protagonists in the this series.
Foe Yay: Much more so than in the original, actually. See the entry for a nice long list.
Fridge Brilliance: Explaining Youma's time manipulation powers and fondness of younger brothers as due to being the forgotten Titan Kairos, Kronos's younger brother. Specifically, the Greeks had two words for time, Kronos and Kairos. While "Kronos" meant the natural procession of time, "Kairos" meant a specific moment.
Growing the Beard: To many Lost Canvas fans, the series only got good starting from the Minos vs Albafica fight.
Ho Yay: For the fangirls, this is just added fuel for their Dohko/Shion fanfics! It doesn't help that every single Expy got very, very pretty.
Minos keeping praising Albafica's beauty or Veronica with Manigoldo.
Dohko/Kagaho's fight has some.
Radamanthys/Regulus on the front cover of Chapter 200 as well as during their fight.
Alone/Hades with Tenma too especially at the moment when he takes Tenma's head in his hands very close to him as if to give him a kiss. This goes Up to Eleven in the latest chapters (past 212).
The Gaiden series is a fuel of this. We have Albafica having Foe Yay with an enemy and being friendly with Manigoldo.
Les Yay: Phantasos, in female form, licking Yuzuriha's face.
Marty Stu: Regulus, Regulus, Regulus. The series just keeps rubbing it in how great he is and keeps noting that he's a prodigy. He can also use two extremely powerful attacks that require the assistance of other Gold Saints all on his own.
Aiacos full stop. He sacrifices each of his underlings just to prove they are tools.
Yoma is not only sacrificing his family to grant his own wish he also made two brothers kill each other for no reason other than having fun.
Rescued from the Scrappy Heap: Not these Lost Canvas characters per se, but when compared to their classic counterparts. Pisces Albafica and Cancer Manigoldo seem to fall under this trope in Lost Canvas, compared to the original series. Pegasus Tenma might also fall under this as he's far more likeable than Seiya to some fans.
One of the first is Pisces Albafica's last stand and death against Griffin Minos. In fact, it is hard not to sob throughout Capricorn El Cid's final scenes. Actually, make that all of the currently dead Gold Saints' final moments, with special mentions to Taurus Aldebaran, Cancer Manigoldo, Scorpio Kardia, Virgo Asmita... hell, all of them. It's all tragic. Damn series premise!
But the one that takes the cake is Unicorn Yato.
The Scrappy: Alone, for his Salvation Plan. Despite being labeled the purest person on the planet, their is a sizable portion of the fandom calling him more monstrous then Hades.
They Wasted a Perfectly Good Character: Aiacos. After his defeat, he starts moping about whether he once had bonds and is interrupted by Kagaho who was sent to kill him. Kagaho instead spares him and tells him to remember his old persona, Suikyo. What does this mean? Who knows? Aiacos never returns.
The Woobie: Crane Yuzuriha in the Lost Canvas Gaiden.