I'm using 7 and it didn't hide or have any impact on my 2 add-ons (adlock plus and telemetry), but still, isn't this exactly why Beta versions are releases, to catch this sort of screw-ups? No big deal, it's just more embarrassing than anything else.
While really the only add-on I ever use is AdBlock+, I just took a look at my extensions and apparently Java Console 6.0.26 is not compatible with FF7. Doesn't seem like it has affected my browsing at all, but still.
It seems like all FF is doing is alienating it's user base by trying to keep up with Chrome. I have been a FF user since 2004 and have never seen so many problems until now with it's newly updated number scheme.
Maybe it's that FF is having issues trying to be the best with Chrome out now. I am not fully sure, but I am not liking it. There may be a day where I don't use FF anymore if Mozilla doesn't get it's act together.
And from the HTML5 games I have messed around with, Chrome is a bit faster in that aspect.
For whatever reason, I have Firefox 7 installed on my computer, but I do my browsing with Nightly about 99% of the time. Very few websites don't cooperate, which force me to bust out IE9. I wish Firefox would just already release a 64-bit version of their browser, instead of something that's a test.