I like how it saves space and weight. It makes it easy to store and move to where you need it. It's great for pots and planters. Just mix what you need and store the rest in a dry place to have when you need it.
Clean, I can store it in my kitchen, no gnats like the stuff I've bought at big box stores. Only drawbacks - it's very light, so you'll lose a little to the wind as you take it out of the bag; sticks to walls of mixing container, so you lose some there too. Don't like losing any of it since it is expensive.