Mozilla has updated Firefox to version 12 today, completing a cycle of changes to how the program updates and bringing some serious elbow-grease to its developer tools.
You still have to you approve the User Account Control (UAC) the first time you install Firefox, but for all subsequent versions, it will automatically update without your approval. This is the same update procedure that Google Chrome has been using on Windows for more than a year with few if any known negative consequences.
Besides cutting down on the your interaction with the update process, one potential benefit of automatic updates is that if Mozilla must release a security patch, the browser's security will not be dependent on your interaction.
This follows changes made in January's Firefox release, which marked about 80 percent of add-ons as compatible by default. Doing so prevented most add-ons from slowing down the browser update process, and it also more closely emulates the mobile app update process.
Developer tools have received a lot of attention in Firefox 12. Following the new ones such as Tilt in the last release, Firefox 12 has made more than 85 improvements to its dev tools. These include fixes and improvements made to the Style Inspector, Web Console, Page Inspector, HTML View, Page Inspector 3D View, Style Editor, and Scratchpad. HTML5 media player controls have also gotten a visual refresh.
You can read the full list of changes in Firefox 12 here.