I wish Mozilla put efforts toward preserving settings and not reinstalling search providers one has purposefully removed. I understand that by using Nightly I cannot expect what a general user expects, but this problem exists in all browsers. I consider it user-hostile behavior that more emphasis isn't taken to preserve settings. Oh a new update? Clearly you want us to sync everything instead of just the few things you selected. Let's revert it all to defaults.
I also understand how settings are stored (the backend format) might change between minor or major versions. Sometimes factory defaults need to be reinstated - but it should be very fucking clear (with a notification) that the user should go review settings that have changed/reverted. And this cannot be a banner that shows every time an update applies. Give the user some transparency.
On Chrome when I ask it to preserve my previous session it preserves just that session's browsing history. This history is forgotten if I make a point to close all tabs and end the session. On Firefox I must save all history be to 'restore the current session'. Wish we had more control over this.
You can't disable Firefox from checking for updates (I wish this could be left to package managers on some systems). I understand but I don't want to be nagged. You can make Firefox ask you, but it will check nonetheless.
Why the fuck would I want "Recommmend features as I browse?" or "Recommend extensions as I browse?" I hate being advertised to.
"Warn you about unwanted and uncommon software" - who is making this determination? Who is Firefox talking to about what I download?
I wish I could sync settings, open tabs, addresses, history, etc - to an simple archive on close or periodically. No online service to sync against with another account I have to worry about.
Sucks that in hotels Firefox determines if there's a captive portal in effect by querying a Mozilla-hosted site (detectportal.firefox.com).
Blah.