A great advantage of global menus is the ease of pointing them with the mouse.
According to Fitts' law, the time to point a target is function of its distance and size. By sticking the menus on the top part of the screen, the vertical dimension vanishes, since the user can just throw his mouse on top to reach them.
Unfortunately, two major design problems in Unity prevents from completely turning global menus to account.
#ubuntu, #unity, #fail - Posted in the Ux category