It's a Scene Viewer and should be rated as such. With that in mind, this is undoubtedly the best Scene Viewer out there. So what makes a Scene Viewer good? The animation needs to be great but also have variety. The girl needs to be attractive but also expressive. There doesn't need to be a complex story but there has to be a reason for the scenes. No gameplay is required, just the ability to change scenes. So lets break it down.
My God the artwork and animation is phenomenal. In terms of quality it blows every other h-game I've ever played out of the water. Quality art and animation is demanded by a Scene Viewer, but it shouldn't be expected to be this good. It shouldn't be expected to be this much better than your average h-game. The sound effects included with the artwork is the cherry on top. I want to mention that the Cowgirl scene is undoubtedly the best h-scene I've seen for as long as I can remember. In addition to the quality, every single scene has quite a few variations within it. If you find issues here then I dunno man, you might want to consider giving up hentai because you're just going to live life disappointed.
The girl is incredibly attractive and has so much expression and emotion in every scene that it tells a story without the need for words. Despite this, there is actually a story. It's a Touhou character but you don't need to have any knowledge of Touhou to understand what's going on. She could very well just be a random cute maid with a lewd and hidden dark side. With that said, the short story that exists is told well and helps tie everything nicely together. There are visual novels and RPG games with a hundred times more dialogue that tell the exact same quality and quantity of story.
It feels weird giving a Scene Viewer a 5/5 rating but anything less feels like a lie. I don't know what else to say.