To be honest, I watched this when i was first starting to get into K-dramas and I loved the story, cast, acting, and ost. The entire story behind Itaewon class is honestly incredibly inspirational as it taught me a lot of life lessons that a lot of people are not willing to teach me in real life. The reason that I titled this great and good is that I couldn't help but feel that their were some points to the story that were lacking. To avoid spoilers I wont go into specifics. However, the first 10 episodes were just chefs kiss and so satisfying to watch as the plot unfolded. However, after the time skip I felt that there were some inconsistencies with the plot. Nothing to do with the actors just bad writing as I guess my expectations were incredibly high because of the amazing first 10 episodes. Only to be slightly disappointed with an adequate but not quiet right end.
Now onto the specifics

Great
First, Actors amazing all around as even though the characters varied and there were so many different emotions showed from dense, psychopaths', sociopaths, butterfly (transformations), and dirt on the bottom of my shoe(people who have watched this know which characters I'm talking about :D) A lot of people often say that the hype behind this show was because of Park Seo Joon. However, I can't really say that because I was new to K-dramas at the time and didn't know anything about him. So I can say this as a neutral and uninfluenced party I loved this shows acting. The actors were all talented and there was incredible chemistry between the two main leads even in their darkest of time

Second, as someone looking to work in the film industry I found the behind the scenes work to be soooooooo satisfying to watch. The actions shots, profiles, angles, and even some discreet pigeon shots (distorted) were all included. So If you are worried about the shots and camera quality, there's no need to because It was Immaculate.

OST- Great, don't know much about music production so I can' get into the details

Inclusivity: I just had to put this in as a black member of the LGBTQ+ community (Biromantic). There inclusion of a black and a trans character in the main cast is something honestly unprecedented in Korea which I will always always always be grateful for. To be honest, the black character did indeed have a meaning to the plot but I feel like he needed more screen time. However, just the fact that he was in the main cast PERIOD will always have a special place in my heart.
The last scene was so satisfying toooo :)
Now onto the Good
I say good because it was just ok, nothing special

Story and script: The writers did a phenomenal job on the script and storyline in the first 10 episodes and I will always consider it to be some of the best intros that I have ever seen in my life. Just the last 6 episodes were underwhelming. They started out so great, but instead of reaching higher heights or plateauing even, the writing just plummeted. Not drastically but there were obvious changes in the script and storyline which tells me that the writers had cooked up a great intro but realized that there were 6 episodes left and were like "oh f*** we have to end this soon what are we going to do? Oh Ik how about a hospital scene those are always good! Oh how about a kind of but kind of not satisfying ending." I don't know if they changed writers at the end, but the close and personal touch i felt at first went away a little at the end because of how rushed it felt.
HOWEVER, I am not dissuading anyone from watching because of the rushed ending as overall this was a great show, that just needed a little more time to develop.