It's probably because besides it being a slice of life manga, the form of storytelling that is being used is quite hard to follow and doesn't flow very well most of the time, and while you see a lot of things happen in a single chapter you don't feel like anything noteworthy happened in it. And sadly i'm finding it difficult to like any of the characters in this which would've made this a better read. Maybe it's just me, but i agree with calling this a "filler manga", because it's what it feels like. All in all, i don't think i'd recommend this to anyone, there are lots of slice of life manga better than this.
Her amnesia is something that might make this more interesting later on, but that's about it. User Twfi said this manga depicts Atami's scenery well so i guess if you have been there before you'll enjoy it more.