I did a quick upgrade last night. A few bugs were found immediately after the upgrade and needed to be fixed but no serious harm was done.
The upgrade includes revamped session and preferences storage. The user-visible change is that user preferences are now stored in the server backend and attached to your user account if you're logging in when saving the preferences. They will be used on other computers, browsers and mobile devices as long as you're logged in with the same account.
The preferences can still be saved if you're not logged in, in which case they're attached to a browser cookie.
A less visible change is that the settings and session cookies set in the browser are now much shorter - just random keys, instead of containing the whole settings or session data. This makes the HTTP requests smaller, which improves network performance marginally. On a slow mobile connection it might actually make a difference.
I don't have a related photo to attach, so kittens it is again! Buxus and Brassia, aged 6 weeks.