What makes the story good is the additional elements such as our protagonist self confidence that hits the roof, likable characters,enjoyable atmosphere, and so much more resulting in a light-hearted and relaxed romcom.
The author's distinguish art style is simple but elegant. We could read the characters expressions, feel their love and sympathy even when no dialog is present and that is the glory of 80's manga.
We have enough character development for such a short story. The leads have great chemistry, and not just them but all the family of the boarding house (Except the grim guy that was left unexplored). No crazy rivals or nasty ones.
It's short, funny, and delightful. It's a 3 hours or less happy pill. Unlike others I don't think it was an open ending, because we knew the characters' feelings, and that goes for the side characters too. It was obvious from how they looked, the way they talked, and all the interactions told us who would end up with who. So it was cool for the manga to end without showing the relations progressing, for me it felt different to not see anyone heart broken or forced into a second relation just to get them out of the way.
Hiatari Ryoukou! is my new favorite romcom that I think will reread it every now and then ♥