Alright... How do I start this?
I mean, the manga started minimally interesting, but it evolved enough to make itself cool, and then it dropped. A lot.

First of all, I must call attention to the oversaturation of the sex scenes. Yeah, I know, "it's an ecchi manga" and etc, but... there are limits. If I was looking for that amount of sex, I'd just look for hentai.

With that out of the way, I can say that it starts fairly good, but just caught my attention from chapter 22 forward - I saw potential.
And then the beach arc kicked in, which made me really like the development of the story. The math girl was really charming and the new characters were interesting! I even liked the plot twist at the end of it. I expected they developed it.
So I waited that they built upon the plot twist, but another arc, with a brand new villain, started, and, as it went on, it just became... boring. But my limit was chapters 74-79 that made itself clear: everything would be solved through "mating". At this moment I knew, the plot just wasn't interesting as it was before, and then I dropped.

If you liked it, nice, but this just made me come out with a bad taste in my mouth. Would I recommend it? Well, not if you want a thoroughly well-developed story, but if you want a manga that's mostly sex scenes and a fairly good plot, go for it.