OK, had the update applied today and got the chance test it out tonight...
It does reduce the brightness of the screen when put in reverse and allows you to see and use your mirrors. GM still didn't provide any way to adjust the brightness, that's a shame since they had an opportunity to fix several issues at once. I now find the display a little too dim but way better and more usable than it was before, so one size fits all with this fix.
If you have the tow mirrors with the rear facing LED lights, they work very well lighting up the area to the sides of the truck in the camera. The area directly behind the middle of the truck is still a little dim, going to mount an LED flood under the bumper to take care of that area as well