Google played well with their new Nexus 5 that brings the New Nexus Launcher and the new Dialer. It’s Android afterall, and all these apps are available off the marketplace and now this Nexus 5 dialer gets the same treatment.
Folks at the Android Police discovered that this app can be manually installed. Furthermore, in addition to the KitKat dialer, you’ll also have to keep the old dialer as well, in order to be able to still make phone calls.
This procedure required rooting your device and we do not suggest you do that. However, you are the best judge of what apps you want on your smartphone so feel free to try it out.