My Nex8000 upgrade went fairly smoothly. I used the SD card. Despite the stern warning not to let the firmware upgrade run while driving, that's just what I did. I wasn't sure if the upgrade would take 10 minutes or half an hour, and I've got a long commute, so I certainly didn't want to add the firmware load time only my commute.
Once it was done, I hit the home button, and it booted into Carplay. It works properly. There's a voice button on my steering wheel, but it never worked with the 8000, and sure enough it still doesn't work, so I have to hit the home button instead.
The only problem I had was when I left work and drove home, Carplay did not launch. The Carplay icon came up when I docked the phone, and a message "attempting to load Carplay" came up on the 8000. But then it gave up, and I still had the Apps button on the top right of the home screen instead of Carplay. I finally came up with the idea of resetting my iPhone (hold the power button for a full shutdown). After that, Carplay worked fine. I wonder if I will have to do this every time I start a new trip?
I am not having the loud POP problem some are getting. I do have a system with an external amp.
All in all I think it's pretty nice, but it's not transformative yet. The speech recognition is leaps and bounds better than what is built in to the 8000. But, and I am being generous here, Apple's Map app sucks. The default views are just not useful, and you can't change them. You can't even pan the map to look around. So while Siri is great for speaking a destination, I don't want to use the Map app.
The 8000/Carplay integration is very, very smooth. Carplay delivers on the promise of the AVIC apps ecosystem. You get a Carplay icon, instead of the AVIC app icon, and it works. All the time. When you hit the mode button, it flips from Carplay back to the 8000. You can even flip back and forth between the Carplay music player and the 8000 music player. I personally like to use Carplay to pick out an album (using siri) and then flip back to the 8000 interface once the music starts playing. I really like how they integrated Carplay with the rest of the radio.
I think that Carplay has enormous potential. The big variable is Apple - will they allow third party developers to create Carplay apps? I'd love to see Waze and a few others as available apps.