First episode is about Miki who starts tutoring as a part time job. Pervy stuff ensues in this house, not all of it between her and the kid she's supposed to tutor. The next episode is about three girls and one older man going lodging into the woods. All in all, there's not a lot of substance in the stories.
Comparing to another hentai released in 1984, Lolita Anime, I preferred the characters in the first episode of Aoi Taiken because they appeared/were older. Otherwise the characterization is pretty shallow.
You could argue that since it's hentai it doesn't matter if the story or characters
pose a lot of depth, and you'd be damn right about that.
But this anime is ancient. It's not going to provide a satisfactory wank either. So by modern standards it would fail in the only job it sets out to do. Or at least it'll make the whole experience terrible. I could maybe see someone beating it to this in the 80s... if live action porn wasn't a thing.
The best reason to watch Aoi Taiken is to gain a little bit of perspective how far eroanime has come.
It's also quite fascinating to find out that those bizarre x-ray shots have been used since the dawn of this medium.