All Statusbar icons are now white, Android has been de-blued, mostly.
That pop up menu when selecting an app is list rather than grid and tapping on the highlighted application uses it the once.
If use a capable Launcher you have transparent Statusbar and Navigation Bar.
GPS as a toggle had gone and new options in Location settings.
New Home menu in settings for selecting launcher.
Condensed Roboto font.

There are others that I can't think of off the top of my head...

Sent from my Nexus 5 using Tapatalk

Not on the Nexus 7 2nd gen: http://www.droid-life.com/2013/11/22/psa-what-some-device-owners-wont-see-in-their-kit-kat-update/

When I turned on my tablet yesterday I noticed that 4.4 had been downloaded.  After reading about the new features, I installed it.  Aside from the little colored circles when starting up (instead of the colored X), I don't see any apparent changes.  Any idea why not?