Well, I decided to upgrade. My biggest concern is the increased nagging, but I figured that the same way I've avoided the nag in the past will continue to avoid the nag with the new update.
Overall, I've got to say that I like the update, mostly just for interface improvements. The entire interface seems quicker to me, not nearly as much lag moving from screen to screen. I like the new map look, with the auto hiding and always on top. The media player seems a bit busy and took me a little bit to figure out, but it seems more functional now that I've used it some. I don't use USB media, so can't comment on that. Obviously, all the interface stuff is subjective and I suppose how much you like it will depend on how you like to set things up and how you use it. I like that it now calls contacts when you click on them or use the voice commands, instead of just bringing up the contact and making you click on the number. It's about time that they added XM categories!
For the little bit I've used it, autopilot does seem to be better at keeping itself centered in the lane. I do not like the increased nag frequency, but there are ways around it. If you do keep your hands off the wheel though (no need for more debate about the merits of doing so), the nag is very frequent, far more than before, and certainly not just when the car is unsure. I've actually found that at times when I would have expected the nag in the past (going around steeper curves), it doesn't typically go off anymore. Perhaps it's because the autopilot is improving and is more sure of itself. But, that's more than made up for by how frequently it does its timed nags now.
While it may already be detailed elsewhere, I haven't seen it, and this thread has gotten long. So, figured I'd quickly outline my experience with what will disable the autopilot for the remainder of the trip.
The first warning is visual, as it has always been. However, the new visual warning has a white pulsing border around the entire instrument cluster screen that increase in intensity the longer you ignore it. If you touch the wheel at any point during the visual warning, it will reset the alert. You can do this as many times as you want without constantly holding the wheel, it's just going to nag you frequently. Fortunately, this visual warning is MUCH easier to see than it was in the past, even if you're not paying attention to the screen and looking outside. I always thought the old visual warning was useless, as fixating inside the car is obviously not feasible. This one ought to get your attention, and avoid the audible warning.
The second warning is the audible one, which temporarily mutes whatever else is playing in your car. This is the warning that I used to find very annoying, because I got it frequently as I always missed the tiny visual warning and hated that it muted the radio, as well as phone calls, when it went off. Fortunately, I think this will be an uncommon warning going forward, given the changes to the visual warning. Unfortunately, this is the warning that will trigger the autopilot to disable on the third time it goes off. I didn't go any further than that, because I can't imagine that people will ignore both the visual and first audible warning, unless it's for testing purposes.
So, if you're one of the people who use the system handsfree, as was demonstrated and intended by Elon, then you're in for a lot of nags! You can get rid of the nags by tugging the wheel as many times as you want, as long as you catch it before the audible alert. And, if you do keep a hand (or both) on the wheel, it really doesn't take much torque at all to keep the nags away. Just a finger or two at the bottom of the wheel seemed to do it for me.
And, while I'm glad that autopilot keeps improving and I personally like the new interface, I am still pretty disappointed with all of the missed opportunities. As has been mentioned, the navigation is still pretty much the same and still missing basic features that should have been added a long time ago. Voice control doesn't seem any faster or any better to me. While the media player UI is better (IMO), it still could be an awful lot more intuitive and still has plenty room for improvement.