I got a set of Riken Snow in January 2024, and drove about 5000 km on them. I didn't drive too much in deep snow or ice, they seemed fine when driving cautiously on snow/ice. As the weather warmed up, and the roads dried up, I've drove them a bit harder on some twisty mountain roads. They hold up pretty nice, the grip is very good on dry roads, but on wet roads the ABS kicked a few times on harder braking when driving a bit more spirited.
I'm driving a Fiat Grande Punto 1.4 T-jet with about 150 hp. The road feedback feels mushy, and the handling is a bit delayed because of the very soft sidewall, large and soft tread blocks. Their build quality is ok, though I've bought a set of Sailun Atrezzo ZSR 2 for summer, and the Sailuns are a lot better built, the tires look better. I might change the Rikens for some Sailun Atrezzo 4 Seasons for the next winter as in the last years, it's snowing less and less where I live.
My usecase for this tyres is not really what they were made up for, and I imagine for mud, gravel or deeper snow would be really good. Also, they are quite noisy (because of the said soft tread blocks). It's not that annoying though. They offer great value for price, and I would buy them again.