Just updated to the latest version now I've seen how to get my tabs back on the bottom of the bar instead of at the top. Only one old extension of mine doesn't work which is a shame but not a big deal. There is an issue though, I can no longer see embedded tweets here. I've tried manually disabling all my addons but still nothing BUT when I start in safemode then the tweets show up and I don't know why it works when Firefox disables them but not me. I've turned them all off, restarted, checked they were still off, no tweets but when I "restart with addons disabled" from the Help menu then it works.
EDIT: OK, searching through the thread for "tweet" and I eventually found a post that referenced Tweets working fine but tracking protection can break it so I turned it off and it worked. Weird. I dunno if I had tracking protection on or off in my older version but when doing the setup of this new one I went through all the options and decided to turn it on. At least now I know why they wouldn't show up.
EDIT2: Ok, today they are back to not working. Even with the tracking protection off. But again, they work in safe mode. I don't know why they started working then stopped...