I really enjoyed myself playing through the first game, but I had a fair share of issues going through it. Notably:
-My dislike of the ham-fisted theming of hope vs. despair.
-The extremely obvious foreshadowing and details that should be apparent to anyone with half a brain. Being logic railroaded - being forced to go along with the characters as they figured out things themselves I figured out three hours ago - is a part of this problem.
-Very obnoxious characters that overstay their welcome without development (notably Hifumi and Toko/Jill).
These issues didn't put a damper on my experience and I enjoyed the cast all having complex characters and motivations (sans Hifumi, Hiro, and Toko/Jill from being flat, and Leon/"Junko" having no chance in the spotlight before their ends). It was really interesting seeing the characters struggle within and without as the game progressed, and the cat and mouse between both the students infighting and the students vs. Monokuma was exciting.

Then Case 5 came along. I figured out the corpse twist immediately from the fake nails that nobody else bothered to linger on at all, although I think Kyoko in Case 6 mentions this was a good thing...which makes it even more frustrating that everyone but her missed such an obvious and important detail. I didn't know about the Mastermind twist but it quickly became apparent which felt annoying that I knew while everyone was in the dark. Granted, that's a me problem but I got annoyed that it wouldn't get to the point, like the section with Hiro thinking Kyoko's a ghost. Still, the fake-out execution got me good and Alter Ego's final act was one of my favorite scenes in the game (cementing both him and Chihiro as my favorite characters in the game). I didn't have much of a good time with Case 5, but I was eager to move forward since Case 5 was setup.

Then Case 6 came along. Here all my issues with THH really come to a head:
-Hope vs. Despair is hammered with all the subtle grace of a children's show moral. I made myself skip portions of Junko's dialogue because she just wouldn't shut up about despair and hope and stuff. It felt really annoying that the themes in the game of human flaws and growing past the pitfalls of humanity's selfish and irrational nature get reduced to simple matters of hope vs. despair. The game did the slow burn of everyone getting pushed to the edge well with Hina I feel having an amazing character arc with overcoming her own despair. Even within hope vs. despair, there was plenty of wiggle room to make the conflict more complex than simply "despair good, hope bad" vs. "hope good, despair bad."
-Nobody connecting the dots with the Hope's Peak memories being gone was exhausting as well even though it was obvious as soon as Chapter 3. However, the Tragedy being a world ending event was a twist that didn't sit well with me at all. Having such a sudden genre shift from a mystery/thriller to an apocalyptic dystopia felt incredibly off to me and entirely out of place with the rest of the game. It just feels like a forced twist that doesn't add anything to the base plot other than letting Junko be all "uwu despair uwu." Speaking of...
-I do not like Junko at all. Her behavior is annoying with her different acts being really gimmicky and lol random with the cutesy persona and royal personas genuinely triggering my gag reflex from me finding them so bad; her sheer lack of motivation outside "uwu despair uwu" is beyond irritating since it gives her zero character depth, a forced motivation to fit the theme of hope vs. despair, and makes a potentially really interesting villain a character more one note than even Hifumi and Toko/Jill who I both really dislike as characters in their own right; and she cannot just shut up. I found myself skipping though her dialogue because she would just not SHUT UP.

All of these issues made Cases 5/6 a significant slog. Although some other cases had issues I mentioned like Case 2 having a lot of focus on Jill who I don't like at all or Case 1/4 being hilariously obvious, none of them have problems as bad as 5/6 do and all at once. Usually a case only has one or two of the problems I mentioned be a a mild issue at best with the hope vs. despair themes feeling natural to where it's not really an issue until it's flatly said it's hope vs. despair. I did have a pretty good time overall, but I don't like how the theme of hope vs. despair got oversimplified in the climax alongside myself not liking the Tragedy twist at all. It's honestly killed a lot of my motivation to play 2 and onward since I fear that this exact circumstance of the things I didn't like in Cases 5/6 will crop up again.