I used to board at a place that the stall next to us used rice hulls. The stall/walk out was shared by two minis. And with two minis' peeing in there and the stuff not being absorbent at all, it got gross looking pretty quickly. It was easy to clean, and I think I remember it being cheaper than shavings, but it looked like brown slush in some areas of that stall, and always got stuck in the fuzzy coats and manes.