So far so good. Tried updating C2 last night but ended up with problem(s).
Downloaded update and initiated update process. Phone booted and update started fine, until I got a message.
It says something like: Sailfish OS cannot be updated. Try again later and a Reboot button down below.
C2 rebooted normally.
I went to settings and selected Sailfish OS updates again. Just when the update window appears, there flashes an error message. The message disappears so fast that I needed take a video in order to see what the message is about 
The message says: Update requires -1 free space. Current free space 0 t.
Then there is link to a guide how to free disk space. Too bad I can’t click the link and see how to free the disk space 
Here’s my free disk space.
I tried using Jolla Utililties → Refresh application db in order to flush out unnecessary packets and free more empty space.
That did not help. But it made Jolla shop lost count what app’s I have got installed. Jolla shop shows now 0 app installed… and when I try to uninstall app from the app grid, the apps just won’t uninstall!
So far I have installed about 20 apps and cannot figure out what has eaten disk space so fast, that there is not enough room for an update to run.
Would have liked to press Factory reset button… but it seems there is none 
… but anyway, I am quite happy with the camera so far. Finally a camera that focuses correctly as Xperia XCompact had a very bad camera focus
P.S. Jollyboys: Video recording crashes the camera app in 5.0.0.5 (Tampella).
P.S.
If someone knows intimately how to clean Jolla packet cache or how to free disk space with command line, please give me a hint.