It looks like to me like hardly anything is compatible with IE11, IE11 enhanced protection mode, most toolbars are not compatible:
3.The Weather channel Toolbar for IE (http://www.weather.com/services/ie7.html) [the insert URL button on this forum isn't working I'm using IE11]
1.www.java.com (I am warned that java is not compatible with enhanced protection mode before using java)
2.www.GeForce.com (using the pinned GeForce.com the main page does not display correctly)
4.www.facebook.com (pinned functionality is broken)
5.www.google.com (the google talk plugin does not enable)
The IE accelerator menu does not appear when highlighting text.