Unity is poor with multiple monitors
Unity has one window list for all of your monitors which is just confusing and obtuse for such multi mons. The 'Classic' GNOME interface is much nicer if you make a panel on each monitor with a window list. The one thing I do like about Unity is searching after tapping the windows key. I found Gnome Do though which pretty much replicates that in a more configurable manner.
I lost patience after the 3rd time the Unity menu failed to auto-hide itself, making it an exercise in precision mouse movement for me to retrieve the obscured windows.
Also why are they making Thunderbird 7 *BETA* the official mail client?