I think it's very wholesome whilst also bordering on complete degenerate bullshit.

I've not seen usagi drop, but from what I understand somewhere in the story it swaps to a romance between the two characters, while before it's a very wholesome story it ends up being an absolute degenerate shitshow. The anime at least manages to steer clear of complete degeneracy, I can totally believe in highschoolers having the hots for a teacher, I remember some girls at my school liked some of the teachers.

Also it's not massively ecchi, and if it is, I must've skipped those parts because I remember it being pretty watchable without having to fling my head backwards in surprise and disgust at the sight of ecchi.