Yugi, unlike his canonical counterpart who is pure of heart, kind and selfless, is portrayed as a self-centered, egotistical jerk who is rarely concerned with anything apart from maintaining his status as protagonist, often whining when others get screen time, and showing little to no care for his friends. It is not uncommon to see him ditching his friends (or attempting to), and often scorns them.
He is rather sarcastic and at times mocks the show's plot, noting when Bakura "explains" how he became a Battle City finalist that they must be as stupid as Tristan to believe that story, or, when Shadi says that the Egyptian gods are alive, stating that that means every other religion is fake and the hokey Egyptian one is the real one, or when he pointed out that Marik's vendetta against the Pharaoh makes absolutely no sense and questions why he felt a dead guy is responsible for Marik's crappy childhood.
He holds a grudge against anyone who wrongs him (as shown after Weevil throws Exodia into the ocean, Joey for throwing a piece of his puzzle, and Kaiba for cheating in their rematch duel). During one part, he couldn't decide who to root for during Kaiba's duel with Pegasus, just because Seto Kaiba had cheated (in spite the fact that what Pegasus had done up to that point was a whole lot worse, and he also says that Seto Kaiba cheating at a card game is worse than how Pegasus stole his grandpa's soul). He develops a grudge against Tea after she tells him she prefers Yami.
He constantly taunts Joey (not too different from the anime) and seems to consider him a very poor friend, as when he learned during the duel with Joey that Marik had arranged that he'd drown as opposed to being sent to the Shadow Realm (poking fun at the fact that that duel was the only one for which the dub did not censor the consequences, as no one suffered it), he states that Joey's friendship is not worth dying for and that even Tristan is a better friend (which Tristan gloated about). However, he does defend him in episode 50 when Johnson tries to convict Joey.
He has problems with Yami being the main character, saying that he gets everything and Yugi Muto himself gets nothing. While there isn't much to say, he does hate Bakura and can never remember his name, although in episode 23 he admits he's starting to respect Bakura for being helpful, until he falls and hurts his "sensitive little bottom" then Yugi tells him to forget what he just said. He also doesn't consider having Yami fight for him cheating, at one point yelling at his friends (and Yami) for saying so. He also can't tell whether he's a main character and doesn't agree that having "Yugi" in the title name (Yu-Gi-Oh!, as it's often spelled) makes him one.
He is apparently so cute that he's been mistaken for a baby panda, even by Yami ("You mean you're not a baby panda!? Wow you're good").
He is annoyed by the fact that he hasn't hit puberty and is short. He also frequently threatens his grandpa, and generally couldn't care less about what happens to him. His favorite catchphrase is "Super Special Awesome," and as shown in episode 41, he talks to his cards when he is alone (and suggests making out with his Dark Magician Girl, which Shadi overheard).
However, like his counterpart, Yugi does have a caring side, though this does not appear very often. Similar to the original series, he saves Arkana from being attacked by the Dark Energy Disc (which 4Kids apparently forgot to censor). He also speaks to Kaiba on the Kaibacorp blimp after his duel with Bakura, arguing with him to put the blimp down so that Bakura can get medical attention. He even volunteered to send his own soul to the Shadow Realm in place of Joey's when Joey is mind-controlled by Marik, though he promptly reverses this statement after he realizes that death is the consequence of losing that duel. He also cares about his friends, even if they annoy him constantly.
The credits in the Yu-Gi-Oh! Abridged Movie state that he will finally hit puberty at age 23, and will still live with Grandpa.
Others see him as special and his hair is often commented on in duels. When Joey when asks his secret to his hair, he says "Loreal, because I'm worth it." Yami Bakura later makes the same joke about his hair when asked by Marik about exchanging beauty tips, even remarking "I think we already made that joke."
He, like Kaiba, hates his own father (and states that he and Kaiba aren't so different) as heard in episode 47.
In Yu-Gi-Oh: The Other Abridged Movie, he claims to constantly see a strange, blue-haired girl following him. Unfortunately, Joey and Tristan don't believe him, thinking that he's gone crazy.
In the Bonds Beyond Time abridged movie, we learn that Yugi will die a virgin and his last words will be "Oh god I've wasted my life."