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.
Arc Fatigue: 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.
Anvilicious: 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", so depending on your point of view, it could be Some Anvils Need to Be Dropped.
Cargo Ship: The author at several points has put in romantic daydream scenes of Moon Young... and Dal Dal's cooked chicken.
Marty Stu: The Queen's fiancee is giving this feeling to good amount of fans, due to being good looking, extremely rich, excelling at pretty everything he does. He makes Jae Gu feel petty and completely insignificant compared to him.
Moral Event Horizon: Han Gyul crossed it the moment he gave Jae Gu's younger siblings food poisoning.
Ho Yay: Jae Gu earns the...admiration of a middle school-aged boy after fighting off his bullies.
What an Idiot: Lee Hye Kyung decided to roll down his window to taunt Jae Gu, while the latter was holding a hose washing his car. The result was predicable.
The Woobie: 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 appartment 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).