@bartzbb While I do agree almost completely with both of you, I can't deny having a sneaking suspicion that the harem in Isekai Smartphone is used as a crutch to not have good character development. That the author chose quantity over quality when it comes to characters (and I think you'll agree that there's a feckton of characters if we count the ones that just get a single appearance).
Don't get me wrong, I love harems. I love when harems actually end as harems and not just one heroine getting picked and all the others get fecked abandoned. If you build a harem (even unintentionally), take responsibility and make them all happy, am I right? But I can't ignore the fact that it's used in many works as a substitution for good characters. I think that this story would benefit from having focused on only one or two heroines that are well developed, but I understand that writing even a single good character is much harder than nine shallow stereotypes.
But Isakai Smartphone is still enjoyable so props to that. Shows that no matter how bad something is when you analyze it, if it has good "chemistry" that makes it enjoyable then it's enjoyable. Simple as that. I've read a few books where I thought "This story is so good, but why the feck am I so bored..?" which proves this to me.