Following my upgrade from Ubuntu 10.04 LTS to 12.04 LTS, my greatest annoyance with the Unity interface has been the way it broke my web browsing experience. When using Firefox I make much use of Control-Right-Click to open multiple bookmark menu items. In Unity, this simply just does not work. The cause of this appears to be changes made to Firefox to integrate it with the Unity global menu. Fortunately, these changes can be removed quite easily. In the Firefox menus click:
Tools > Add-ons > Global Menu Bar integration > Disable > Restart now
Now the Firefox menus will respond correctly to Control-Right-Clicks.
Disabling Global Menu Bar integration also means that the Firefox menus stay at the top of the Firefox window instead of going up to the global menu bar. This will please my wife who found Firefox under Unity very confusing: "Where have all the menus gone? Where's my back button? Where's the address box? What have you done to my Firefox? It no longer works. I want the old one back". I suspect that these reactions will be fairly typical of the majority of Ubuntu users.