It would be more impressive if I understood how big of a change this actually was. There's very little context in this post.
What was the previous filesystem, and how different was APFS?
If they both operated on the same core principles or underlying code, then the migration might have been trivial. Is it just a new "skin" on the prior FS?
If it's a radically new filesystem based on all new concepts, then that's a much bigger feat of engineering.
What did this new FS accomplish? Was it faster? More reliable? Easier to work with? Added functionality?
What was the previous filesystem, and how different was APFS?
If they both operated on the same core principles or underlying code, then the migration might have been trivial. Is it just a new "skin" on the prior FS?
If it's a radically new filesystem based on all new concepts, then that's a much bigger feat of engineering.
What did this new FS accomplish? Was it faster? More reliable? Easier to work with? Added functionality?