I really wish they'd stop with the quick releases. Several essential add-ons I use for work haven't been supported since 5.0, and my IT says they aren't going to redevelop them until 7 is out. Damn you firefox.
WTH?? FF 5 was released to virtually no fanfare, and very recently at that! It's like they're scrambling to get something out that's better than what's already there, but FireFox is already one of the best browsers. Maybe they should slow down and concentrate their efforts on building a totally new, from the ground up, browser and let FF5 mature a little. With all the addons and about:config console tweaks, 5 can stay viable for years.
Okay I downloaded FF6, and only difference I noticed so far is that notification for the site being opened is slightly above the bottom of the window + it is consuming 20+ mb less with 6 or so tabs I usually have open at any given time. So all in all, I'd say it is just a change of number.
I hated 5 so much with the stupid font rendering with hardware acceleration on and the huge cold loading times that I went ahead and got Aurora (7.0 a2). It's great, it's fast, font rendering is fixed, all my addons work (granted, I only use 4 of them).
But still, people are right. Enough with the silly release schedule already, this is not Chrome. This new update cycle only serves to alienate people that love their addons and "getting up to Chrome's numbers to look more advanced" is ill motivation indeed.
Addon compatibility is the main reason I switched to Chrome for a while and I assume many have followed a similar path. Mozilla should stop this silly practice before it does even more damage to its reputation.