The big problem with this adapter is that we don't have other options, but NEED something to shoot our "legacy" Nikon glass on Z bodies.
I purchased this to use my 600mm F4G on my Z 9.
The good:
VERY good performance. Very speedy; no issues acquiring focus or tracking. No performance issues in this regard.
The bad:
Very poor fit. It has a sloppy fit that I would maybe expect from a cheap third party white box adapter. Using my Z9 with the 600mm makes me cringe even on a tripod with how much it twists. Maybe there is a reason for using such loose tolerances, but wow...it does not inspire confidence. I'm also disgusted with how expensive this is...doesn't Nikon want us to move to the Z mount?