Well, it ended the way I thought it would so what else can I say.
My thoughts on Natsuiro Kiseki:
Slice-of-life series are a dime a dozen, so I have to admit that most of such shows these days tend to bore me unless they have some sort of novelty or fresh idea to distinguish itself from others. Natsuiro Kiseki is yet another addition to the typical summer-themed four-girl slice-of-life genre, and its novelty comes in the form of the granting of miracles in the summer, a season the Japanese seem to cherish when it comes to having fond memories. I suppose that some of the hijinks they experienced are mildly interesting, but they're nothing worth commending in the grander scheme of things.
Perhaps the main issue I have with NatsuKise, apart from the run-of-the-mill content, is the production values. It's derpy; it's so easy to see the flaws in the artwork, and it's kinda sad to see them especially when the aesthetics is the one aspect that the show could've taken full advantage to render itself more watchable.
It's a 5/10. My inner cynic tells me that NatsuKise is a mere career vehicle for SPHERE. It's just like most shows these days that feature Mizuki Nana: the series don't mean much, and they're there just to promote Mizuki's music career.