FINALLY got my update a bit before 9 PM last night and it took almost exactly 2 hours to install. Since it could be months before I need to drive at night, I went out with the purpose of trying out the new headlight behavior. First off, the lights did not default to bright so I set them manually. Driving Route 66 on the east side of the mountains from Albuquerque after 11 PM does not yield a bunch of oncoming traffic. In fact, I had the road all to myself. So I tried out Dream Drive. No joy, it needed to calibrate again.
That might all sound like a bust, but not so fast. I drove west on I-40 and kept trying Dream Drive. Finally, after the highway widened to three lanes, I pushed the button and the message said, "Hands Free Driving"! I kept my hands near, but it did the job without any glitches. I got back on Route 66 eastbound to return home and met up with a couple of cars. The lights did not work like the pictures suggested; a sharp gap in the light beam to protect the oncoming driver. Instead, I first noticed that nobody was flashing their lights at me. Then I noticed that the light on the left embankment was lower than on the right. After the oncoming car passed, I noticed the light smoothly move back up. Very impressive!
I tried engaging Hands Free on the two lane but, about 8 seconds after letting go of the steering wheel, I got the warning to take control of the car. I tried multiple times to no avail. So I went back up on the interstate and Hands Free worked just fine. Got off and it would not engage. It still worked as before this update; it would steer the car but still demand that I have my hands on the wheel, so no real loss on the two lane.
A couple of other observations: It seems that the music sounds even better, but that could just be my excitement. And I can now send a navigation destination to the car from my phone, a feature which worked when I took delivery of the car on Christmas Day but quit after a following update.
Overall, I'm very happy with the update.