I've used it and still have some. It's a nice substrate but not that grippy making planting hard if you either have fish that uproot plants, or heavy flow. I had it for 8+ years in a tank and it looked no different after that time to when it went in, so it doesn't degrade and has good longevity.
When first setting up I just washed it and then let it soak in water for a few days and this stops most of the floating grains which I believe is just trapped air.
There are perhaps better substrate for promoting plant growth but it's a nice inert substrate.