intro arc: 2/10 at best (awful introduction to the premise, too much focus on bakugo's shallow character) USJ: 8/10 sports festival first half: 6/10 sports festival second half: 8/10 stain: 5/10 finals: 5/10 season 2 wrap up: 3/10 training camp: 9/10 rescue: 7/10 license first half: 6/10 manga, 3/10 anime (really, really badly adapted)
manga only... license second half: 6 or 7/10 bakugo vs deku: 8/10 seniors and internships intro: 7/10
overhaul stuff is kinda difficult to break down piece by piece because it's made up of a lot of different parts. some go together well and were executed nicely. others were clunky and hard to follow. the action scenes in the manga suffer from this especially. lots of clunky scenes across all of the arcs mentioned above where it can be annoying to try and figure out what the hell horikoshi is trying to show us.
anyway the notable standout above is probably my low rating of the stain arc which a lot of people love but probably for all of the wrong reasons. I get the feeling people don't understand his character at all, but keep in mind he basically just shows up, vaguely disagrees with another villain without giving too much context for why and how they disagree, and then he gets promptly defeated and never shows up to do anything relevant again.
series definitely "gets better" in the sense that the first arc is completely awful, but I doubt anyone with more than 2 brain cells would dispute that. the series as a whole does follow the general pattern of having a lull of weak or mediocre storylines with brief upswings, but to somehow infer that one story arc being bad means that every story arc for the entire rest of the series has to be bad in the same way is completely moronic.
I think the whole point of Stain is not what he does in his arc, but what his actions do to the world.
It's the first major crack in super-hero society. It questions the legitimacy of super-heroes. And it empowers villains.
I feel like the show is building to some huge destruction moment, where the protagonists will have to take over and save the world, and so far all the arcs have been a chain of events leading to that. Stain is like the first event.