I'm sad because it is over, and also because the ending is kinda sad (and also hopeful) too.
I liked this manga. It took a lot of clichés (harem, overly-nice-yet-still-pretty-generic MC, et cetera), and makes them work in a somewhat novel fashion without turning into a full on parody/deconstruction.
I mean it was short, but compare it to something like Nisekoi. Without spoiling anything Nisekoi is" all clichés, not interesting, super long; and it has a dumb ending (in my opinion).
Although, one "fault" I have with it is that ghost-girl's kinda sad story/existence gets a little sidelined with all the SS-tier waifus kicking around. The ending does remind us that she exists and that the whole harem thing was her scheme to not be alone anymore.