It seems to have subtly broken TreeStyleTabs on OS X, which is a shame because I am addicted to it, but at least it's still usable (the tabs take up ~150 pixels of vertical space). Hopefully this will resolve itself with a TST update.
That said, wow, the OS X improvements are huge. Previously I could only force quit if I wanted to shut down to free memory or whatever, but now it closes normally. I'm also not seeing the same kind of memory usage, but it's early so I'm not sure how long that will last.
It's purely the visual component I mentioned, the functionality seems to be okay, although it's reported as broken in the add-on manager. I have the tab bar docked on the left vertically and the tabs are ~3x taller than they should be.
I'm the same way about switching to Chrome, by the way. I would love to but I just can't picture life without TST after so many years.
I don't see the tabs taking up extra vertical space, although 3x the size should absolutely be noticeable. I did, however, have a problem yesterday when watching a fullscreen video: if I put my cursor on the left side of the screen, the tab bar would appear (as though I had it set to auto-hide) and obscure that portion of the video. It was quite annoying because the sensitive areas extended all of the way to the top left of my screen, where I have a "corner" set up on my Mac to disable the screen saver.
Ah, you know what, I just figured out what the issue was. I was using the "metal" TST skin and when I switched it to another one, the 150px-tall-tab problem went away.
That said, wow, the OS X improvements are huge. Previously I could only force quit if I wanted to shut down to free memory or whatever, but now it closes normally. I'm also not seeing the same kind of memory usage, but it's early so I'm not sure how long that will last.