FF has for me crashed more times in the last week than in the previous year. - Multiple installs on different Linux systems. The last crash was with a clean profile.

And then there's the disappearing dev tools - that's fun.

EDIT: I hope that there is something weird with my systems. But I fear that the rush to push this out might have been a little hasty.

EDIT EDIT Apart from the crashes the new FF has been nice. I've been able to largely stop using chromium for dev work - so not all is bad.