The writing overall is good, decent characters, plot and development. And the main cast are not complete idiots on the level of self sabotaging cucks you'd see in most isekai.
The big problems tho:
1) It tries to be about "avoid politics" and just one man and his band of friends, except they are strong enough that they are politics. It's realistic, but the mood whiplash makes it jarring to read.
1.5) Similarly, it tries to be both "slice of school life" and some war story (one that's more grimdark than the author intend) and it does not really work. The switching around gets jarring.
2)The villains r total scum, they do exactly what the nobles did to them but to others, making them worse as they at least knew what suffering was. Also, boring.
Their motivations are all over the place, from" for some reason experimenting on foreigners instead of their own countries ppl that they hate", to I am driven by rage, other countries didnt save meh, to apparently i can control my hatred, i'm only in this for survival or generic greed. Boring. The hunter girl band seemed interesting at least.
3) mind control is the most boring element in a story ever invented in history, it is dull to read in every way possible.
4) their combat tactics are complete shit for what kind of power they do have. too many villain stage exits and not enough scouting or assassinating.
5) the trashy romcom gag of interrupting every romance scene, the romance at least progressed, but honestly it's not much better.
TLDR: tries to be both slice-of-life and a war story, doesn't pull it off. the war story is also darker than the author thinks it is
It's kind of a pity, for all the good parts it has, i dont like it enough to follow it.