The new Firefox has not so many new characteristic than the older version. Even though these changes are visible.
In this version Mozilla has implemented an improvement in Http connection managemet. Inactive tabs on your browser consume less resources and as a result better performance is achieved. In this version there are also upgrades for html 5 platform, canvas, MathML,Smill and XHR protocols. Small changes but vital in the constant upgrade of the software.
You can download the new vwersion or upgrade you current one (if you already did not) here: www.mozilla.com