Look, I like cutesy stuff. I like reads that simply pander to otakus like myself, and having a purpose like that is not shameful or wrong. To bash this manga, or any similar work, for its simplicity and lack of substance is missing the point of it. You could say, however, the work is good to a certain, low degree.

With that said, "Please Don't Bully Me, Nagatoro-san" is not a good manga, not because of its simplistic nature, but mostly because it's monotonous and repetitive. In every chapter, it follows a the same old linear narrative from start to now. Nagatoro essentially repeats same kind of shallow banter to Senpai, to which he reacts in a painfully expected ways. For a couple of chapters, the manga's cuteness and adorable nature stays fresh in our minds. But, repeat the same thing OVER and OVER again with little variation and dull plotlines, then its novelty quickly wears off, and the impression on the manga becomes that of an annoying puppy.

It's got no merit to it. It doesn't try to develop its characters in meaningful and relevant ways. Senpai is a timid and weak; he has no friends, can't speak for himself, and lacks any social confidence. He starts with flaws, and the story could've focused on his realization of this and his progression towards becoming better. But as expected, this kind of character development does not occur. I will say, there are moments where Senpai tries becoming assertive, but they're spontaneous outbursts that aren't attempts to deepen a character, but to elicit a shallow appreciation for his brave moment and create an opportunity for us to uwu at Nagatoro's subsequent cute reactions.

At heart, Please Bully Me Nagatoro-san is a one-trick pony. Its a cute manga that loses its cuteness within few chapters.