The moral that "It's not wrong to physically fight back against your bullies and sometimes that's the only way to make them stop bullying you" is a pretty decent one, but it gets hammered in hard. That said, it's a moral that's rarely brought up in favour of "Just try talking things out with the bully".
The author really doesn't seem to take smoking well. It's rarely brought up in the series, and the few times it has, the character is being highly unpleasant while doing so. There's Shin Yoonji, who is a Bitch in Sheep's Clothing, there's the three unnamed middle school girls who absolutely brutalized Dal Dal, and tried to do the same to Moon Young, who was not in a Heroic BSoD, and those three teen terrors were actually middlemen for Han Gyul, the resident Evil Redhead.
The stagnation of Jae Gu's development after he finally gets Han Gyul to stop bullying him has not sat well with a lot of readers; often sighting that there has been no relevant plot to follow other than seeing what the current cast, including Jae Gu, have been up to as they go about their daily lives, and introductions to several new recurring characters that have their own bullying problems to deal with. All of which had been stalling the finals of an ongoing Tournament Arc! The plot finally returns to focusing on Jae Gu with the introduction of an Arranged MarriageStory Arc (which is more focused around Queen rather), but its still developing at a snail's pace.
Some found that the underground fighting matches against Jonathan's henchmen lasted a bit too long, and wanted the series to finally move on to something else.
Jae Gu's Love Triangle arc between Queen and Dal Dal had gotten stale over time. The plotline was around since the very beginning of the series, and was on full-force with the beach-trip chapters. Most complaints were either that Jae Gu had been too indecisive to just choose Queen over Dal Dal, or that Dal Dal had clearly lost the love-war, and should just step aside before becoming too annoying and desperate as she attempted to stay relevant for Jae Gu's heart.
Chapter 255 is universally considered the breaking point in the Unresolved Sexual TensionWill They or Won't They? overriding plot between Jae Gu and Queen, as Queen considers calling Jae Gu on her phone to find out why he's late to the amusement park, but ultimately does not, and Jae Gu completely forgets he has one on a two-hour drive from where his younger sister is hospitalized to the Amusement park to try and reach her in person before she's taken out to the airport for a several-years education outside Korea. While some fans have loudly voiced that a simple one-panel shot of Jae Gu trying, and failing, to use his phone to reach her would have saved the series, just about everyone is ready to Rage Quit altogether.
Chapter 257 is regarded by the fans as adding insult to injury with the reveal that Queen is auditing classes in Tokyo U and In Seoung, her younger brother, points out that Jae Gu could easily go there, as it's a mere two and a half hours away, and he doesn't even need a travel Visa. Making most readers wonder if the Manga's end is coming soon.
Base-Breaking Character: Dal Dal. On one hand, some fans have fixated on her deliberately cute, bubbly personality and mostly self-inflicted heartbreak concerning Jae Gu to the exclusion of all else. Often ignoring the fact that she's not actually in love with Jae Gu but with the notion of being in love, and Jae Gu is merely the target of her obsession, and the fact that she is far more skilled, talented, and experienced than he is and reacts rather violently to any suggestion that Jae Gu might be off-limits to her, oh, and she knows where he lives. On the other hand, many fans find Dal Dal annoying, at best, as they have fixated on the fact that Dal Dal is constantly trying to force herself on Jae Gu, feels entitled to have him be her boyfriend (as seen in chapter 193), regardless of any attempts to rebuff her, and her creepy stalkerish behavior, often showing up at his house, without notice or invitation, sometimes ignoring the good things she has done, like protecting Jae Gu from Jeff, or Jae Gu's younger siblings from Han Gyul's gang, although the latter was a team action including Moon Young and Queen.
Cargo Ship: The author at several points has put in romantic daydream scenes of Moon Young... and Dal Dal's cooked chicken.
Jae Gu earns the...admiration of a middle school-aged boy after fighting off his bullies.
Queen's grandfather has an interesting reaction to Jae Gu rescuing him from falling down some rather steep stairs while the former was following him home, ranting and raving.
It becomes even more dubious when Jae Gu applies some pain medicine to the man's back after the elderly gentleman starts showing signs of extreme back pain. It is not explained if the pain is a result of the near-fall or is part of a chronic condition.
Memetic Mutation: Happy Fathers Day!note Dal Dal's father saving her from a group of kidnappers on the exact day of Father's Day in real life caused a lot of these kind of jokes.
Han Gyul crossed it the moment he gave Jae Gu's younger siblings food poisoning.
Johnathan crossed it the moment he ordered Jeff to brutalize Jae Gu.
Ship-to-Ship Combat: Jae X Qu vs Dal X Jae has become official on both sides of the fourth wall, with Queen and Dal Dal engaging in actual combat over Jae Gu. It took Moon Young pointing out that Jae Gu had neither knowledge or consent regarding the fight to make them stop, and all that did was put it on hold...
They Wasted a Perfectly Good Character: Lee Go Seul. She started off the series as a fun recurring character alongside the other three main females that provided Jae Gu a helpful female friend who wasn't trying to become romantic with him. However, she continued to decrease in relevance to the story as the series went on, and no longer makes any more meaningful appearances after the Wild's Tournament.
Despite being a major plot-point as to why Jae Gu and his siblings are living a rough life at the start of the story, whatever happened to their mother that abandoned them is never delved deeper into.
Apart from the Garbage Ring duels against Jonathan, the martial-arts aspect of the series has taken a backseat in favor of daily-life / romance shenanigans amongst the cast. Many current readers are hoping that the webtoon will finally return to the fighting roots that got them hooked on the series in the first place.
As mentioned in Arc Fatigue above, many were more interested reading the webtoon for Jae Gu's underdog story to become a better fighter rather than getting wrapped up in his Love Triangle romance drama later on.
There was a brief point in the story where Jae Gu ended up having a nosebleed due to overworking himself. The amount of Wild Mass Guessing that surrounded this event as to what was wrong with Jae Gu was mind-blowing, but then led to major disappointment when it didn't lead to anything major in the next couple chapters, and was then completely forgotten about.
The series coming to an end after 260 chapters came as a shock to a lot of people with many wondering if the author just got tired of continuing Girls of the Wild. What happened to Jae Gu's mother? Where was the payoff for Jae Gu's siblings being geniuses in certain areas? What was the point of Queen's fiance? Why was the later half of the series almost nothing but relationship Love Triangle drama instead of returning to the martial-arts aspect that people read the series to begin with? The series in general left a lot to be desired.
Jae Gu's been through hell and back. Dead father? Check. Abandoned by his mom with his small siblings? Check. Needing to do a part-time job to guarantee his family survival, with loads and loads of self-sacrifice for them along the way? Living pretty much in poverty? Cruelly bullied by his ex-classmates without EVER reacting? Three times check. Seriously, he's been through so much shit he can be considered the basic model for this trope. And now he's even forced to move out of his shabby apartment due to his landlords selling their estate, which leaves him and his sibling homeless (The last of which gets thankfully averted by Queen's younger brother just moments after).
Dal Dal has her fair share too. As she hopelessly falls for Jae Gu and does her best to win his heart, she is deeply hurt when he is still completely oblivious (and after she's made him meals, casually called him "hubby" and kissed him... twice) and does not return her feeling. Nevertheless, she still tries her best to act cheerful and carefree so as not to upset him.
After Dal Dal accidentally overhears Jae Gu's (almost) confession to Queen, she comes home, crying profusely all the way. The following day, she skips school and tries to spend her day without thinking about Jae Gu, ignoring his messages. At the end of the day, as Jae Gu visits her out of concerns. Seeing that she's seemingly okay, he prepares to leave when...
Dal Dal (starts crying): I'm the only one who's hurting! Why do you have to come and smile like nothing's happened? Just go away! I'll just hate you for today! I'll love you tomorrow!
And she puts on her cheerful face the following day like nothing happened. ** Now Queen is starting to get some woobie points in recent chapters. Being sent into an arranged marriage to a guy who, at best, sees her as a company investment, not as a person with thoughts and feelings, is friends with a Straw Misogynist who thinks nothing of trying to ply her with alcohol in front of her fiance (who then does nothing about it), deliberately making her as uncomfortable as possible, and when she rightfully tells him off, with a proper slap to the face when he tries to force himself upon her, sends a cameraman into the bathroom to take her photo, without her consent, deliberately letting her hear the camera flash, but not letting her know the nature of the picture(s) in question.
The attempt to recover those photos winds up as a massive "Shaggy Dog" Story, as even though Ina is able to grab the memory card, Jonathan has already uploaded copies to the internet, forcing Queen, Moon Young, Jae Gu, and a few others into an underground tournament with his top 5 fighters, with the promise to return them if they won. Instead, despite Wilds High ultimately wiping the floor with his fighters, not only does he give orders to advertise the photos (which he claims are of an intimate nature), but he demands the entirety of Queen and her allies bow before him and apologize for the fact that he is antagonizing them. When this does not go the way he wants, namely Jae Gu sucker punching him in the gut after Ina gave him a free shot, he calls out the REST of his fighters to Zerg Rush Queen and her allies who are exhausted from the tournament. Fortunately, her bodyguard, Driver Park had the foresight to place YK security on standby.
Lastly, Jonathan found out Moon Young's and Jae Gu's home addresses thanks to Queen's fiance, who despite having been personally attacked by Jonathan and his bodyguard, Jeff,after Jonathan confessed to being at fault by sending a cameraman to take her photos in the bathroom right in his face, still feels compelled to blame the whole thing on Queen and happily gave that information to Jonathan, believing the guy is his best friend, and that Queen played him, ignoring the fact that all his own actions to date have done nothing but alienate her, and rightfully so. Thereby allowing Jonathan to not only ambush Queen and Moon Young in their sleep, but threaten and attack Jae Gu, who is Queen's primary love interest.
For bonus points, if Queen ever spits out her feelings for Jae Gu, she will alienate her own family (with the exception of her younger brother who respects Jae Gu after being beaten in a practice match, and being given an appropriate scolding regarding his attitude during said match), especially her grandfather whose word is LAW in Queen's family, and made her childhood a hellish experience by forcing her to look and act like a boy, constantly shuffling her around from school to school, tutor to tutor, country to country, and making finding a friend nigh impossible. Talk about being Blessed with Suck!
The clincher? Dal Dal rubbing her face in it broke her completely. She is both visibly shaken and moved to tears. This is something that has never happened in the story before, regardless of the situation.
Dal Dal catches the woobie ball again in chapter 231. Say what you will about her, nobody deserves to go through that. NOBODY!
