The star of the Naruto series is indeed Naruto Uzumaki himself, the orphan boy who grew up to become a splendid ninja of the Hidden Leaf Village. Naruto gets more screen time than any other character, meaning his personality, motivations, and backstory are all explored in great detail. As a whole, Naruto's personality is a mixed bag.
That's not a bonafide problem, though. To be a relatable and balanced shonen hero, Naruto needs as many faults as strengths, and his personality certainly has some rough edges to sand down, especially at the beginning of the series, when Naruto was bitter and had everything to prove. Which aspects of Naruto's personality reflect poorly on him or interfere with his progress as a ninja?
10 Naruto Can Be Uncooperative At Times
This negative aspect to Naruto's personality was fixed fairly early in the series, as Naruto learned to become an integral member of Team 7. Academy students are graded from A to F in several fields, and one of them is cooperation. Naruto scored a solid F in that department.
Naruto, for many reasons, didn't get along well with his peers, and he wanted to do everything himself. This once bode ill for his future career as a ninja, and he was the type to charge into danger while leaving everyone else behind. That can be a real issue.
9 Naruto Has His Petty Side
Naruto definitely acted his age at the beginning of the series, being a prankster and all. He still didn't get along well with other people when he graduated from the academy and joined Team 7, and his petty side emerged when it came to Sasuke and Sakura, and even Kakashi Hatake.
First, Naruto pranked Kakashi as retaliation for being late to the team's first meeting. Then, Naruto tried to one-up Sasuke as a romantic rival to Sakura by capturing Sasuke and taking his place while using a transformation jutsu. This is definitely not Naruto at his best, and he has formed other petty grudges since then, too.
8 Naruto Has His Dishonest Side
Ninjas are all about deceit and trickery during missions or in a fight, but Naruto takes this too far at times. He has been known to act dishonestly, trying to acquire things with petty lies or schemes rather than earn them.
Naruto passed the chunin exam's written sequence without even answering the questions at all, which vaguely troubled Ibiki Morino. Naruto also tried to eat lunch behind Kakashi's back, despite a punishment that forbade eating. And those weren't the only times Naruto tried to do something behind someone's back, against their wishes.
7 Naruto's Vanity Pops Up Often
Naruto's many issues lead him to having low self-esteem, so he compensates with a boastful attitude. He claims to be the best ninja of his generation, if not of all time, and this annoys his fellows to no end. He was all bark and little bite early in the series, and he even claimed that was unfair for a "great ninja" like him to be teamed up with the "loser" Sasuke Uchiha.
When Naruto faced a roomful of competitors before the chunin exams started, he shouted his name and declared that he would defeat every single one of them. Sakura was furious, but Kabuto Yakushi took note. How interesting this boastful young ninja is.
6 Naruto Is Reckless In Many Situations
A proper action hero needs to be brave and proactive to get the job done, but many hotheaded shonen leads, Naruto included, tend to be downright reckless about it. These characters can quickly get in over their heads once they jump right into a dangerous situation.
Naruto recklessly slipped inside Haku's ice crystal mirror array to save Sasuke, which ended up doing little good. Naruto also got a little sloppy and carried away while fighting the Six Paths of Pain, and nearly got himself captured until Hinata Hyuga showed up. And more than once, Naruto recklessly ran off to confront the rogue Sasuke, despite the danger.
5 Naruto Is Self-Absorbed, Making Everything About Him
This is related to Naruto's vain side. A person can be vain, but also be quiet about it, thinking to themselves that they're the best. Naruto feels the need to actually tell everyone about it, and he tries to make everything about him and his needs and wants. At first, Naruto had a hard time putting himself in anyone else's shoes.
Naruto had had no friends growing up, and thus he wasn't used to the give-and-take nature of friendship, where the parties fairly split the relationship. Growing up alone and unwanted, Naruto determined that the only person who (apparently) cared about him was, well, him. It took Naruto some time to unlearn this.
4 Naruto Is Sometimes Spiteful
This personality trait is more distinct in Sasuke Uchiha, who often scorns and derides other people who are viewed as inferiors. But early on, due to his vanity and self-absorbed nature, Naruto was also a rather spiteful person, always willing to contradict other people and get in their faces.
Naruto ridiculed the entire village, and the office of Hokage, by vandalizing the Hokage monument over and over, and he humorously humiliated Iruka Umino when he unexpectedly performed the Sexy Jutsu rather than following classroom directions.
3 Naruto Can Be Blunt & Tactless
Naruto is often seen as a bratty kid, and not without reason. In addition to being self-absorbed and boastful, he can also be rather blunt and insensitive with other people, despite his position. He grew out of this before long, though.
If Naruto doesn't like someone, he doesn't mince words at all; he'll directly say "You're the worst!" or "I'm taking you down, jerk!" and anger everyone in the process. He's also quick to bluntly call most people a perv, from Ebisu (who reacted strongly to the Sexy Jutsu) to Lord Jiraiya himself. Naruto needs to find better ways to phrase these things.
2 Naruto Is Stubborn
This is another negative offshoot of the "brave and proactive" character model, along with sheer recklessness. Naruto is quick to get ahead of himself and jump into trouble, and he does this often, despite everyone else scolding him for it. Naruto isn't so easily talked out of a situation.
Naruto's stubbornness can take many forms, from his refusal to listen to Iruka during his academy days to his dogged insistence on searching for Sasuke when he should have spent more time on training. Naruto needs to be more flexible and take other people's ideas to heart more often.
1 Naruto Is Deeply Insecure
This is certainly Naruto's worst personality trait, but unlike most of the other negative traits, Naruto can't be blamed so easily for this one. Naruto grew up without a family, and no one liked him or respected him at all. Naruto tried to compensate with his vanity and boasting, but that's surface-only.
Naruto received zero support or validation from anyone else, and this made his heart heavy as a result, casting inner doubts on whether he can truly become accepted and rise as a great ninja. An isolated kid like Naruto needs a lot of guts just to show up to the academy since it would have been so easy to quit out of despair. Fortunately, Naruto indeed had the guts to persist.