The rollout has been "slow" for Kit Kat due to bugs that were caught before the update was widely distributed. A new build is being sent over-the-air as of this moment. If you have a Nexus device, you will get yours soon. Or maybe not.
So far, I feel like things are every so slightly smoother and swifter. I'm not sure if it's real or something my mind made up. As reported in other outlets, most of Holo Blue has been excised, although not completely. It remains so that you can see check boxes and toggles at a quick glance. Otherwise, the whole thing would've been muddled in a sea of gray.
I've also sideloaded Google Experience Launcher, which puts a Google Now pane left of the home page. The icons are much larger. The notification shade and the on-screen buttons now are transparent; however, since this is not a Nexus 5, it does not get transparent bars on the lock screen. Speaking of the lock screen, I can finally disable pesky lock screen widgets from the security options instead of having get a work-around elsewhere. One more thing. After having had the wallpaper bias be in the middle, the GEL's left bias for wallpaper setup annoyed the hell out of me, but it's a non-issue.