I think it is great for aerating soil and I use a lot but mainly because e don't have diatomite or other alternatives here. You can get it easily and in specific sizes. It also makes the pots lighter for handling and can be crushed by the taproots as they expand so there are still air spaces in the soil.
The probs are the dust is really very evil and irritates lungs, eyes even skin, so it must be damp when used. It is not carcinogenic like asbestos because it is amorphous as opposed to crystalline, it is actually heated basalt rock that puffs like popcorn at high temps and becomes a type of glass. Also if there is no top dressing then it will float to the top of the soil when you water so you need about 2cm of gravel on top to hold it down.
Other issues are the energy used to mine and pop it and the possibility of it blowing around in the wind and becoming litter. It lasts for ages in the environment so getting rid of old soil becomes an issue.
One last issue is that it has trace amounts of fluoride that can damage leaves on susceptible species like yucca and dragon trees but cacti have no problem wit it..