Well, right now, there's not much to review. It's an early prototype, although I'll definitely keep an eye on it. It avoid so far a lot of the jankiness of similar games, where everything feels a bit too "floppy" (aka the old "touch the breasts a little too much and your fingers will either bend backward, clip through the girl's model, or disform the model in a really weird way").
It's not the case here: Primerose's body is "firm" enough to withstand manipulation without things going horribly wrong, visually. It may even be a little too firm, though, as her boobs seems to mock and defy gravity itself, lacking a bit the more "real" feeling a tiny little bit of sagginess or weight can give.