According to what was shown in the changelog from the beta version, this release will not bring any important security fix or any function that is of major consequence and justifying an early update, however the stability and full support for extensions can suggest that Firefox users already use this version.
The news, as already mentioned, appear to us coming from the beta version, which does not seem to be any new feature added last minute, or until any correction. Firefox 12 basically brings the update process for Windows users, the new version reduces the number of warnings for passing only a single. It also improved the system downloads, now whenever you paste a URL in the download manager, the download will begin immediately.
Another change relates to where is presented the search results page, now appear in the center. It was also corrected a bug in the Mac version of Firefox that caused performance degradation with user contents when they were WebGL.
There are some fixes that were reported after the release of Firefox 11. One of these concerned the slow scrolling window bug in Gmail, which some users were able to report. You can confirm other corrections taken into account here.
OS: Windows, Linux, Mac
Download: Firefox 12 Final Windows EN [15.6MB]
Download: Firefox 12 Final Linux EN 64Bits [18.9MB]
Download: Firefox 12 Final Linux EN 32Bits [17.2MB]
Download: Firefox 12 Final Mac EN [30.1MB]