My take is that it’s a good start and important step towards fully de-leading the fleet fuel. There was a good article on AVweb breaking down the difference between the STC and ASTM approaches and the work that still need to be done:

https://www.avweb.com/uncategorized/eagle-and-gami-not-a-transparent-process/

If you own a plane, do you intend to buy the GAMI STC for it?

Do you have access to G100UL at your airport or in your area?