The lack of tab separators and the poor contrast between the tab bar and the rest of the chrome are my biggest issues. Chrome has both tab separators and higher contrast between the tab section and the rest. And of course, the old Firefox design also has tab separators and very high contrast.
One of my biggest complaints about Firefox is how much work I have to do in my userChrome.css to make it look nice. My current one is almost 400 lines and it's mostly adding separators/element padding, changing border radiuses and disabling hover and focus styles.
I never wanted a carbon copy of Chrome, just something that looked good, so I'm glad to see Firefox provide a nicer default experience and add its own unique style. It's actually pretty similar to MaterialFox anyway, aside from the "floating" tab style and slightly higher vertical space usage.
Not really, theme is currently only allowed to alter css variables(basically colors). There is a special type addon that do allow to alter the browser theme directly (behave like userChrome.css). But that requires addon signing from mozilla and enable certain hidden control in about:config. Basically not likely done by a general user.
that and the container highlight has moved to the top of the tab. On windows 10, i am having a difficult time identifying which tabs are in a container and which are not...
Hm, your tabs don't have favicons. I can still clearly differentiate tabs because of the spacing, though I guess if you had a lot of tabs with very minimal spacing, you might get some visual ambiguity.
Personally, the previous design was fine and this one is too. Neither has made any meaningful difference to my user experience.
Edit:
Scratch that. I've just noticed that tabs can now have a sort of status line, telling me, for example, that's it's playing something. There was functionality sort of like this before, but this is a nice improvement. Great.
This addon looks good, but I'm too tired to have to relearn new locations of elements, differences in UI, changes in context menus every 1.5 year Mozilla decided to improve shit. I've been using Firefox since Phoenix 2002, but this time I'm giving up. Moved all to Brave Browser.