My big annoyance is the fact that when I hover over a link, the URL no longer shows in the task bar at the bottom. I honestly only realised how much I used this when it disappeared.
A bit of searching suggests that it is something to do with the Status-4-Evar add-on, which I'm reluctant to bin. I'll give it a few weeks and see whether between them Mozilla and/or the add-on developer come up with something.
A rare visit to a Windows partition revealed that all my add-ons are "legacy" (the Linux version doesn't seem to show this) - and will no longer work from Version 57 (I think) - can't remember the details about why; some fundamental coding change in Firefox. I suppose I should look more closely, but in the meantime will try to remember not to update from 55 until I know my favourite add-ons have become compatible.
The add-ons are the main reason I use Firefox, for goodness sake. That, and the fact that I don't trust Chrome - for all its undoubted merits.
Sorry, Aerne - no ideas about the arrows. Mine still seem to work - although all that side of things is dependent on Status-4-Evar and Classic Theme Restorer.
When things aren't broken - why do developers insist on fixing them until they are?