I have been using an iPod Nano 7th generation for a couple of months now. I got it to replace a Nano 4th generation which has a problem with the clickwheel.
Compared to the older Nano I really like the interface. Sound quality is excellent with my Sennheiser earbuds. The FM radio is very decent too. But a really nifty feature is the addition of Bluetooth audio, which worked really well with the replacement VW Golf I drove when our own Golf was being serviced.
Our own Golf has the bog standard RCD310 head unit to which I had the VW iPod cable fitted. It didn't work great with the old Nano. I had to create playlists in iTunes and then copy them to the Nano. It works, but it doesn't show track titles. At least with the new Nano I don't have make playlists anymore. The VW cable isn't great, but at least we get sound and I suppose the good thing is we don't get distracted by track information while driving. Of course we had to buy the 30pin to lightning adapter for the new Nano.
Managing podcasts however is a bit weird. Rather than dragging podcast titles to the trash, you now have to unsync them in iTunes.
I tested the Bluetooth function in a Mini as well, but the machines wouldn't pair. If you have Bluetooth audio in your car, your mileage may vary with the new Nano.
My other half has recently got a new Nano as well. We also have a sound dock, so we ended up getting 2 adapters. One for the car, one for the dock. At least the adapters charge the Nanos. We bought one Nano when we were in the US. I couldn't believe that they are cheaper in USD than in EUR here in NL.