For Windows users, the most significant development is the built-in PDF viewer. Yes, just like Google Chrome, henceforth we will not require another piece of bloatware to read PDF files, instead we can open them and read inside Firefox 19.
The difference between Google Chrome and Firefox is the way they read the files. While Google Chrome uses the proprietary Foxit Reader plugin to render PDF files, the developers at Mozilla have taken a different route.
There are 3 bug fixes and improvements about which you can read at release notes:
Firefox 19 has also been released on Android, however I am unable to install it on my phone. Even though the Mozilla claims Firefox 19 is compatible with Android 2.2+, I cannot install it on my Android 2.3.6 mobile.