It's good but it also bad; it'd pretty average. I have things to complain and I got things to praise about. To sum it up, the cons of this drama outweigh the pros and I couldn't avoid to notice them. Let's go.

School 2021 is the latest drama of the KBS School franchise which was meant to be School 2020 but covid19 caused the production to delay and they had to postpone. Although there were uncertainties about starting it in 2021 even but thankfully, they aired it, even so it now ends in 2022.

There is no solid plotline. It's simply is a mixture of many subplotsz keeping the romance plot at the center. Corruption reveal, friendship, bromance line, love triangle, family relationship, etc. are a part of the story. They probably wanted to make the highschool corruption the central plot but it was inconsistent and didn't work at all.

The key difference between previous dramas of the KBS School series and this one is that, the school isn't an ordinary one, rather a specialized skill-based school where students are trained in particular vocational curriculum. It actually could have been a better show if they had made a script about different aspects of such schools, but duh! The thing is, this script could have been any other highschool drama but it didn't fit the concept of the KBS franchise, it didn't have anything that we see in the School series.

Again, no solid plot and hence no steady development; the mixture of different element, makes the overall story messy. The first 2 episodes didn't make any impact as introductory pieces, it wasn't bad but not something to keep you on it. The next few episodes were smooth and gave off an impression of an average show, and I, somehow, wanted the show to retain the same quality till the end but even that was inconsistent. I admit, I somehow got myself emotionally attached till 6th just to get myself disappointed after that. I pushed myself to finish till the end, only because I am bad at giving up , otherwise I could not find a single reason to motivate me to keep watching. It went downhill in the 2nd half and the blame goes to the writers for getting lost within their own script.

Gong Ki Joon (Kim Yo Han) is basically a looser but got character development and his acting improves with episode though it stayed pretty average till the end. Jin Ji Won (Jo Yi Hyun) is a determined and hardworking girl but very typical and outdated of a classical Kdrama FL though her acting is up to par. Jung Young Joo (Choo Young Woo) is a terrible actor and he never improves, adding to it, his character in the drama was such needless and stupid one; he deserves minor roles and not SML.

Special mention to the SFL Kang Seo Young (Hwang Bo Reum Byul) who despite the least experience did the best among the younger cast. Not just her character was was a potential strong FL, she did a splendid role in playing it.

Ji Ho Sung (Kim Kang Min) and Go Eun Bi (Seo Hee Sun) are the 3rd couple with shoddy backgrounds and stupid plots.

Lee Kang Hoon, Park In Hwan, Kim Gyu Sun, Lee Ji Ha, Kim Min Sang, Jo Seung Yun, Kim Soo Jin... are some of the very good actors in this drama but it's such a waste of their talent and time as they didn't have the scope to showcase their skills. The overall acting department, hence, is a big turn off and another reason to drop this.

Kim Min Tae PD a comparatively lesser experienced director but the only 2 dramas he produced before this were actually moderately good shows, Idk what went wrong with the direction here. The screenplay and it's organization were one of the major disadvantages. The pacing is equally messed; both unnecessarily slow and fast at times. I didn't know about Dong Hee Sun jakkanim and I can't really judge from her previous work since I haven't seen any of the 3 movies created by her. But judging the script of this drama, I am sure she had a difficult time writing a drama script, which is a lot different from a movie script.

There are plots of many types which needed a lot better execution but those rather ended up being puzzled. The distribution of plots and elements should have been fairly distributed but they're rather dispersed unmannerly. They either concentrate one subplot too much or forget about that completely. Same goes for the characters, who, in fact, have no solid dynamics to back their personalities. There is no impressive character development either. Simply put, so many unnecessary subplots and so many unnecessary characters.

OSTs are moderately good but not really memorable. I liked "Way to you" by Rosanna the most of all, followed by "Recently" by uri Yohan. "Dream on" by Na Go Eun is the only track that matched the drama, others are mostly romantic songs, and very unrelated to the drama. "Absently" by SWAN and "Can't help loving you" by OMG Mimi are tracks with the vibes of classic Kdrama OSTs.

Things I liked...
# The 2nd Female lead's acting... She was the only one among the younger cast who could act and not just acted, but did very well. In fact her character was the only one with amazingly painted arches; the only reason I went through the ending.

# The love triangle here isn't a mess. It doesn't last long, or turn into a toxic pull and push game between the main cast.

# The first Male lead wasn't very flashy unlike other highschool Kdramas where the FFL is some sorta genius who can do everything; the one here was a loser and we saw a character development for him with each episode though it wasn't really impressive.

Things I disliked...
I have a long list :3

# the 1st Female lead needed more exposure bcs she was supposed to lead the show. I didn't completely dislike the character but it needed some background and a character development method.

# There were relatively less school scenes for a "School" series drama and that too the school scenes were very unappealing.

# There are way too many characters than needed. Not just in School series, also in almost all highschool dramas, there are many students in the supporting characters, but here, there were less than 10 students directly involved whereas others were absolute fillers with 0 contribution to the story.

# Honestly, no romance could have been okay given the genre but I don't really complain about it's existence. The thing that made me off was the overal plot of both the couples. In terms of chemistry, the 2nd lead couples were better but neither of them were really good.

# The mixture of lots of plotlines was a bad decision and in the end, they were missing out on the development of each of the plots on a great deal.

# The not so cool "boys let's punch and make it up" kinda bromance did cut off some points.

#The stupid and entirely unnecessary plot for the 3rd lead couple s, which absurdly funny and could have been avoided.

I came here for Yohan as he's a sweetheart to me. Plus I was excited to watch a drama of School series after 3 (4) years. Another reason that had my anticipations up was the fact that it was delayed a lot. But all my expectations have been crushed and I am left disappointed by the results. I don't at all mind average dramas and okay with a drama not having typical stuffs but it should be a decent watch, which School 2021 wasn't. Even if you don't compare it to previous dramas of the series, this one as a light drama by itself is a failure. I have seen better light themed shows to give this a pass.

Overally, it's pretty average, in fact below average in terms of production values, acting and more importantly, the the entire outcome. I wonder why this show was even made. They should have skipped the entire script or made another highschool drama bcs KBS School franchise is a different thing in whole together and it's a shame this drama let the essence down. I am disappointed and I will suggest you to drop it without even starting.

P. S. Gave it 6.0 only because it's not very bad and I think I am being generous.