Like a lot of other commenters, I came close to quitting this manga. The slapstick and tough love of Al's family, especially his sister, gets very tired, very fast. I'm also not a huge fan of the worship of modern food these Isekai mangas all seem to indulge in. Must entire volumes be devoted to these people trying to get / develop rice, miso, and soy sauce every time? In the end, though, I'm glad that I stuck with it. By the time he and his parents go to the Royal Capital all of that stuff calms down quite a bit and his sister's stupid antics become much less frequent. Which is a good thing because, when Al interacts with other people like Roomba, Tri, Bartolo, and, in the more recent chapters, the adventurers who are escorting Tri's caravan, this manga becomes downright hysterical.
It's a gag manga, so cartoon violence is kind of expected. So long as it's kept low key and rare the way it has been the last 30 chapters or so, I can live with it. I'm hoping Al starts interacting with a lot of other characters from now on and I have high hopes for his sister's absence while she's in the capital studying with the knights, away from the family. Al's not spineless, he's a kid, whether he has the mental development of a 30+ year old or not. He's a wise ass who's enjoying his new life the way he couldn't before and, despite his complaining about people taking advantage of him, he likes making the people around him happy.
So, the story's worth sticking with, honestly. If you really can't stomach the sister violence, stick with it and skim a bit until chapter 40 or so. It gets better. The later chapters had me laughing quite a bit.