Received my C2 today.
It was switched off and charged at 48%
Charged up to 80% before switching on
At the first start-up, I dared to choose the language (German), thereafter entered and confirmed a 6 digit security code (that replaces the default security code), did not skip connection to local Wi-Fi but instead connected to Wi-Fi, signed up to my Jolla account, installed all suggested apps and waited until the set-up wizard finished and the tutorial appeared. I skipped (closed) the tutorial and updated to 5.0.0.21 via settings menu.
The automatic reboot during installation of 5.0.0.21 was the first reboot.
Everything went fine and as expected
The hardware looks and feels better than expected (my expectations were low, admittedly)
The device feels slower the Xperia 10iii