I feel like there should be a different word than ecchi to describe content that focuses more on boobs than any the story.

I think there was an episode and a half of content solely dedicated to planning for and then buying a bra.
The girl having amnesia was not indicated if that was entirely a fabrication.
The writers attempted to use misdirection and hidden information. These inconsistencies lead to a disconnect for me, making the reveals seem forced or contrived. It may have been their intentions but I feel as though the true nature of the characters was intentionally obscured. I like consistent storytelling, even if it isn't straightforward.
The humor and fanservice give you whiplash when placed so close to scenes attempting to build character complexity where the main character states his real kid sister is dead when he is unconsciously groping the girl and then IT IS NEVER MENTIONED AGAIN!?

Also, this is tagged as harem on some locations, but he does not acquire a harem in the true sense. It's just the standard formula of females join him to fight. One male with multiple females is FAR more common than a team of multiple men when it comes to Isekai.

TLDR: There are some cool scenes, but there is too much time wasted on talking about boobs.