There's something quite unique in Mayfly renders: currently most 3D visual novel graphic renders are either on the realism side (Leap of Faith, DIK, Broken Dreamers, Race of Life etc.) or adopt an Anime-Realism blend (Eternum, Pale Carnations, Stormside etc.). There are also a few odd ones that are fully 3D Anime/Hentai.
Mayfly on the other hand is the only VN I have seen so far that sits at a space somewhere between the Anime-Realism blend and 3D Anime/Hentai spectrum. It sort of resembles in style to some FF games yet also has a certain ethereal quality similar to some 2D Anime renders.
Pros is this is currently an untapped space and a niche can be carved out, cons is many players who prefer models built on realism might find this even further departure from convention hard to swallow.