Works as advertised, but lacks option to selectively disable or use specific timezones on certain sites.
Many sites will not work with this enabled including those "protected" by googles already broken recaptcha. On these sites you end up in an endless loop of recaptcha prompts and are unable to login and/or access content.
Add an option to disable or select a timezone on certain sites and it would be a whole lot more useful.
There isnt even an option to disable it from within FF, other than disabling the whole extention in FF options.