I've never used it to be honest, but I've heard different things about just the clay. Some people like it and some don't, the main issues I've heard being that it is hard to clean and a pain to replace completely. If your guy doesn't poop on it then that's a moot point, but with how heavy it is removing and cleaning and then completely redoing it would seem difficult. I've also heard that once it's dried and set it doesn't really allow for digging.
It's fairly common to use a loose nonbioactive substrate, although I see it more often as a dig box or just in a section of the enclosure and not the entire thing. One mix I've thought about using but haven't yet mainly because mine does poop in his tank is 50% fine play sand, 30% organic topsoil and 20% excavator clay.