So I installed the new version today to find that the about:config tweak for disabling check.extensionsCompatibility no longer works.. I did some searching and found, Add-on Compatibility Reporter,After installing the Add-on Compatibility Reporter, your incompatible extensions will become enabled for you to test whether they still work with the version of Firefox. it worked for me. If you were wanting to upgrade to the new version of Firefox but did not want to wait for an update to your extensions give this a try.
https://addons.mozilla.org/en-US/firefox/addon/15003