The NFC unlock with skip was already part of the November update, IIRC.
The differences that I have noticed:
- when you press the home key while using the stock launcher, it always brings you back to the default home screen, even if the last used home screen was another one. It's almost like you pressed home twice. It's a little annoying.
- if you have two apps that can do something, with nothing set as the default (say, two browsers on the system), the first time a browser link is pressed a list of items is shown, allowing yo to choose one and choose a button that says "Just once" or "Always". That's not new, but what is new is that if you select something and say "Just once", that item will be highlighted the next time you have the same choice.
- there is a full-screen mode for apps that support it. The first time you see it it tells you that you can return to normal with a swipe down from the top.
- if you turn on "tap to focus" in the camera app, there is a new focus/white balance control that you can drag to a focus point and then tap anywhere to take the photo and use that as the focus point (and, as I said, to control exposure/white balance.)
- apparently it supports BT LE devices like the Fitbit, and supports tap to pay for Google Wallet (though I use neither of these so cannot confirm for sure.)
- the status bar remains black and the battery status and time are still blue, with the network icons remaining blue for Google connection and gray for no Google authentication, and they also still show network activity (this is unlike the Moto X.) There is a new location status icon that looks like a white Google Maps place point icon. For some reason the network icons look different to me, but they may be the same.
- there is now an unlabeled icon to clear all notifications in the notification shade, and the settings page icon looks a little different. Also, the settings gear icon looks a little different.
- there is a setting to allow you to set the default messaging app.(settings->more [under "wireless & networks"]->default SMS app)
- there is now a settings->printing setting (I don't think that was there in Jellybean) and I have printed from GMail, Hangouts and Chrome.
There really isn't a whole lot that's different or that looks all that different. (I probably missed some things...)