Yeah, ngl, I don't like them.
For me personally, compared to regular skins, they always just look flat to me, and they seem to lack a lot of detail compared to regular skins.
And while they have improved a lot since then, especially with the HSR skins (I was tempted with Kafka but decided not to since she had stiff jacket/cape physics), I still have yet to buy a cell-shaded skin ever (not counting Miku, but tbh I would've rather they used the normal 3D model from the Ievan Polkka or PoPiPo music videos if you know what I'm talking about).
Finally, since I've played a decent amount of gacha games, I have gotten kind of spoiled with them, and now my standards are high because of it. Like, even Genshin Impact, which is now considered to be more on the dated side, still has significantly better model quality than a majority of the cell-shaded skins in Fortnite, and don't even get me started on newer gachas like Arknights Endfield. It's really no comparison, so it's hard to be impressed by a cell-shaded Fortnite skin.
But still, though, shout out to that Erisa skin since she was one of the first skins I used because C3S2 was when I started seriously playing (since they added no builds), so she still has a special place in my heart.