It has a weird acceleration curve that no other mice I've ever used have. When you physically speed up movement, it accelerates the pointer too much, and when you physically slow down movement, it slows down too much. I find myself frequently overshooting or undershooting the "target" because of this. I just got an iMac and I thought it was just how Mac handles the pointer, but nope, I connected a Logitech mouse and it feels normal, so it's just the Magic Mouse. Maybe the older ones didn't do this?
If you've spent decades using normal feeling mice, I can't imagine getting used to the Magic Mouse because normal pointer acceleration is like muscle memory at this point.
Furthermore, there isn't really a comfortable way to hold it. I am convinced that it was created only to increase the perceived luxury of Mac product accompanying it and not for function.