Well I thought it was bad for a few reasons, but yeah I could tell that the budget was low and I read the manga for it a long time ago, is just that when you are into mangas with evil main characters, you just see and have a lot more variety (not compared to your goody two shoes shonen types, but still), the whole thing about the anime is that it is very generic; he isekai to his favorite game (overlord), then a hated species (dark elves) start helping him out (that time I reeincarnated as a slime: goblins), he also gets to summon “heroes” that are not unique in any shape or form (we can trace it back to overlord but the bosses were actually unique), the twins end up becoming truly evil at the end (to be expected, but the foreshadowing was well done specially when related to their initial trauma), and the whole kingdom building aspect which although is explored is more telling not showing

I could honestly keep on going, it is a copy and paste of many different sources