Mozilla has just released the third Beta release in the Firefox 25.x branch, and it's now available for download and testing, on all available platform.
Firefox 25 Beta 3 has been released without much fuss and there aren't any particular details about this version.
The Linux binaries for Mozilla Firefox 25.0 Beta 3 are available for download and users can run them in parallel with the existing installation of Firefox.
In any case, the current beta version sports quite a few changes and improvements. The biggest one is probably the one related to the “find bar” which is no longer shared between tabs.
Remember that this is a development version and it should NOT be installed on production machines. It is intended for testing purposes only.