They can read data from ALL websites you visit while using this.

This does not actually work. Maybe Facebook has found a way to circumvent the addon? Because targeted commercial pops up all the time on my Facebook based on pages I have visited I give this addon 1 star.

Not work at all !!!
Even i use this ext, facebook knows where and what i visit. Advertising on facebook match exactly with the sites and interests i've visited just before open facebook.
I do not understand why !

This add-on breaks the ability to use Facebook to login into some other sites. Worst, it just results in a blank login page on some sites (like cbc.ca) so it wasn't clear that it was caused by this add-on.