Cluttered top-nav is a hassle to use, with the worst offenders making me feel like I'm looking for a needle in a haystack every time I use it. It's much nicer to drill down to the section you need one step at a time without modal navigation windows appearing and disappearing, especially if the defaults are well-chosen.
[It's also worth noting, as mentioned by others here, that the paradigm of stacked windows, and thus pull-down menus, is incompatible with pocket OS designs, so you're going to end up with completely different navigation workflows on different platforms if you go this route.]
Also note that this nav and template isn't unique to the homepage like most higher Ed institutions but is used site wide by all units. That was an epic battle story for another time.
Personally I like any menu system that has search in it. So that first 2-5 times I use search, then I learn the location and can click the right thing directly.
dropdown menus should be abandoned since they
rely heavily on the hover state
Further, a menu with a responsive design, such as the following, negates the need to abandon anything:
> http://jasonweaver.name/lab/flexiblenavigation/
I ran some tests on this menu. It fails on android 2.3.x and 4.x. Also does it really need JS to function properly. No it doesn't, CSS already has all the features needed.
By the way, the unified drop-down menu style could be incorporated into a menu that has responsive design, such as the following: