At the surface I had a similar experience to what the author describes. The movement feels good to me (until it doesn't), the game is appealing in style and gameplay concept, and I die frequently.
But unlike them I dropped it after throwing myself at the exact boss they mention.
Not because I think the game is actually hard at this point (it seems quite early in the game), but because I don't think the game actually respects my time. Something they don't seem to have an issue with.
They mention that they died over 30 times to the boss, and how it never felt unfair to them. And while I do not fully share this sentiment, I do not actually mind that part either. The difficulty of learning a boss is part of the game.
What surprises me is the not really mentioned part, that these 30 deaths (if I were to take them) take up 1-2 hours of my time.
And you might be thinking, 2-4 minute boss fight? Seems reasonable? To which I say, this person focuses so much on movement and dying to random stage hazards because at least 70% of that total time is spent getting back to the boss to begin with, a 1-2 minute run of the same segment of game, each attempt!
That's right, I spend more time running to the boss, than actually fighting it, because it turns out that you make mistakes when you do something repeatedly, even if it is just getting to the boss. I wish I could learn the boss and "get gud", but the game just won't let me without wasting my time.
Part of that is a skill issue on my part of course, but for this very segment at least, you just start to see all the little hazards the devs have placed on the optimal path, to trip you up if you ever lose focus for a second. For a part of the game you have already done, and are not actually concerned with at that very moment.
At least for me this got tedious very quickly. And supposedly this actually gets worse in later parts of the game.
At some point you start to wonder, "is the game punishing me by making me traverse the game world before fighting the boss again?" And this thought starts to infect the regular gameplay, were you are supposed to willingly explore the game world, you know, the core of a Metroidvania.
At the end I just asked myself "why am I willingly playing a punishment?"
The author even seems to have vaguely similar thoughts here, they say themselves that they are sometimes not having fun with this core part of the game. Isn't that worrying from a game design perspective?
Anyway, I think that's enough ranting, sorry for not concluding this thought.