I think they're a fun and challenging exercise. I've done them after front squats as a way to get more leg work. They're similiar to front squats in the way that they allow you to work the legs without loading the spine. Not loading the spine does come at the cost of putting more stress on the knees on this exercise, so it's still a kind of double edged sword. I can't even do them anymore, due to having a torn meniscus on my both knees. But it's probably okay, if it doesn't hurt you.