The development version of Firefox 30 is now hit Beta 7. Firefox 30 features the new, better user interface “Australis” which was introduced on Firefox 29.0. Firefox 30 comes with some new features such as support for GStreamer 1.0, Sidebar button gives easier access to social, bookmark, & history sidebars. This link explain details of any new features and changes to Mozilla Firefox 30.
If you want to test this Mozilla Firefox 30 Beta 7 on your Linux distribution, simply follow these instructions.
Open Terminal and type this command to download Firefox 30 Beta 6
Or you can browse for other language and architecture from this link.
Next extract the file
tar -xjvf firefox-30.0b6.tar.bz2
It will produce a new directory called firefox. We need to move this directory to /opt/.
sudo mv firefox /opt/firefox-30
Backup the original firefox link
sudo mv /usr/bin/firefox /usr/bin/firefox_backup
Now create link to the new Firefox
sudo ln -s /opt/firefox-30/firefox /usr/bin/firefox
Now your original Firefox is replaced with this new one. Or you can also run Firefox with command