To be fair those aren't the aspects I don't like about Subaru. I'm fine with his crying, depression, and insanity. I'm fine with him being a shitty swordsman. I'm fine with his consistent dying.
It's his intelligence that irritates me. He's dumb as bricks. It took him painfully long to realize that he has the ability to return after dying, despite having memories of what happened previously.
I was willing to let that go and he did show some form of intelligence in the Mabeasts arc when he asked for information about curses and planted a trap with an escape strategy to figure out who the murderer was.
But then the next arc happened. His behavior around Emilia, and his irrational behavior at the palace is absolutely horrendous. He's just so stupid.
I'm fine with him making mistakes. But he just doesn't seem to get it. He doesn't learn.
I was told that it is still too early in the series. Maybe he grows as a character, I don't know. But right now it's irritating to watch him make the same mistakes, be consistently stubborn, and show no level of self growth.
It also makes no sense to me that he finds so much comfort and passion towards people he just met like Emilia and Rem and Ram (when he says "I loved you guys"). But maybe that was just inadequacies in the writing more than anything else.
Subaru has the potential to be a good character, who fails and has flaws, but because of his ability he figures stuff out and succeeds in the end (the way he has overcome problems so far is usually via plot convenience rather than anything he does in particular).
He falls short of that expectation.