I watched this drama before reading the webtoon so this is my opinion as someone who didn't have any idea about how the original was, and I have to say, had I been a webtoon reader first, I might have not enjoyed and liked it as much as I did. If you are a fan of the webtoon, I'm going to be honest with you and say don't watch this, more on that in the end of my review.
I tried not to spoil anything but there's a bit of spoiler at the end.

Story:
It consists of two arcs, basically, and they're very different from each other but that's what makes this drama special, along with the characters' friendship. I've seen people saying that the villain just turned out of nowhere, and I have to ask them, were we watching the same show?

I started the show expecting classroom fights but it's much more than that.

Acting:
The whole cast absolutely crushed it, especially Park Jihoon and Hong Kyung, for me, the latter made me feel every emotion his character felt, and I clearly saw the shift, they both did an exceptionably great job in the last episode, I couldn't go through it without tearing up every few scenes, even when I rewatched some scenes alone.

I don't really have much to say about the music so going to the next thing.

Rewatch Value:
The easiest 10 ever, I wasn't even done with the last episode when I thought "I have to rewatch this show sometime" it just feels like it'd be better with each rewatch because you'd be able to spot more details.

---Spoilers---

And now, to the Webtoon fans, why shouldn't you watch this? It's just too different from the source material, I'm still just where the flashback ended in the webtoon so I might be wrong, and if I am I will change this part but as of now:

The first half is basically non-existent in the webtoon, with original characters and events. I'm not sure if they, like, took it from later on in the manhwa and tweaked it to fit the begging but from what I see it is original to the drama.

Even with the main characters (the trio) they are very different here than in the manhwa, I don't want to spoil much but the fights start from the very begging and it's almost like SE (Gray) and SH (Stephen) switched roles at times, and I'd say BS (Bryce) is the biggest change in terms of personality, they made him a whole lot more tolerable and likable here, and the trio has more of a friends dynamic compared to the webtoon, SH is also very different, he's a fighter here, but he's still the very good friend he is in the webtoon.

My take? Do watch it, just not as an adaptation but rather as it's own show, approach it an open mind, and the change in names will help you see the two versions as two different things mostly.