Compliments?
Really, seriously?
It is such a usability disaster!
Removing the separators between tabs makes just a row of icons and text.
The floating bubble for the “active” tab makes it just hang there, visually, totally disconnected from the content pane. So clicking it has no link for your brain that it will switch content panels, like all other tabbed UIs do.
The extra row of text in the title bar of tabs just distracts and clutters: when I open 10 tabs from a youtube page I do not need Firefox to put a text in each titlebar that background playback was blocked!! That little icon in the old UI was far sufficient for that and much, much, much less cluttered! It was quick to learn what it meant and did not add clutter because it did not require an extra line in the tab title bar.
Really, I was shocked to see this new UI after updating last night. It’s an instant-hate for me.
I instantly disabled FF auto-updates on my other machine, started switching themes to see if that would restore sanity (alas, no), and today started frantically searching for ways to leave feedback to Mozilla that this needs fixing!
I signed up for a forum account here only to scream from all rooftops that this is a disaster that needs fixing but alas, I’m afraid the UI dev team is deaf to user complaints as I see that the same complaints have already been voiced since April.