Can't say I'm a fan of this. The new redesign looks dreadful; the weird floating tab button thing looks like a UI toolkit bug or maybe someone trying to fake tabs using buttons, rather than an intentional design choice. As other commenters have noted, there is also now no visual distinction between open tabs (tab separator is gone) - how is the user meant to tell that the non-open tabs are even intractable UI elements, let alone distinct from each other?

The menus and omnibar look the same to me though, for better or worse.

It seems like FF is getting worse with every release. Who thinks the changes (read: regressions) over the past few versions are a good idea? Who is the target audience of FF?