This is the best execution of the high school setting I've seen so far, and it demonstrates very strong character writing and a good understanding of mental maturity, while still covering a lot of interesting themes. Front and foremost, MC is already quite likeable with interesting trauma, that he satisfyingly works through in a very clear way, and his development feels substantial throughout. He serves as a well-thought-out standpoint for the audience to project onto: he's just like us, being plopped into this completely foreign environment with people who aren't like us. (It especially hits home if you're the target audience, a japanese working man in his late 20s working a job going nowhere, I would imagine)

There are also very satisfying developments throughout, and the show's not afraid to show people making mistakes. It's well-paced, stays interesting, explores some interesting perspectives on life, and has some great ideas. Not many characters were unlikeable, and when they were, they learned from their mistakes, and it was a relatively believable depiction of them acting their age. It's all to further drive home the divide in mental maturity, emphasising this gap in lived experience which is done consistently throughout. It's also just a fun concept to begin with, so it's not hard to get into from the get-go.

My only major complaint is that the music is pretty bad all throughout. The production value is low, and there are some highly questionable musical decisions being made that do not match the mood of the scenes they underscore. There's like a few canned tracks they reuse repeatedly, which is not abnormal for anime, but if they're going to do that, they can't have each track making some jarring decisions that only make sense in specific contexts when they're meant to have a deeper emotional outcome. If they're jarring decisions being made in contexts where the music is only being used as a fairly-surface-level emotional grounder, they simply clash with the intent of the scene, and take the audience out of the moment. It sounds cheap, and often fails to deliver on what is expected of it, taking away from the scenes instead of enhancing them. It wasn't completely irredeemable, but it was very below average.

Still highly recommend overall. If you haven't seen it yet, I would highly recommend checking out the Final Arc OVA after watching this. It's one of the few anime that I can think of that don't drag on or never end, it just concludes its story, definitively, without any reservations, and in a very satisfying way. I've seen similar anime (one very popular movie specifically) mess this up for me, so take advantage of it while it was actually done right. The following spoiler relates to that final arc, and sorta spoils some stuff in this main season:

This one is worth checking out if it seems like your sort of vibe.