The main thing to keep in mind, to rephrase an Author Comment, "The Story line follows Emotions, not Strength".
The Novel is not about the MC getting stronger, and as such, although the MC is getting very strong very fast, this is kept very condensed. Basically all Chapters are focused on the Love Interests.
In the beginning the MC is very naive, which is deliberate as he grew up very sheltered and is not reincarnated/transmigrated or anything (so no Meta knowledge). Among other things he wants to only marry one Person, although even then he loves both his Senior Sister and his Master, but thinks he can't marry his Master. This changes around chapter 90 when he admits to himself that he loves more than one person - and, considering some things revealed later, this realization is actually rather important for the story. The Author made it very clear that this emotional development of his is deliberate and was meant to happen from the beginning.
The relationships with the FLs are written quite good, but the start of the relationships are often very shotgun-like (lots of 'love at first sight').
Probably one of the Best Harem Focused Novels out there. At some points it will feel like there are too many coincidences and that it seems quite 'deus ex machina', but these things are actually intended, so don't let them turn you away.
All in all I have to say it fells like a novel written by an actual Author who thinks about Plot lines and has an Idea of what he is doing.