Unfortunately, not much unless express/remote windows or one of the new colors excite you.
Note: No official order guides available as of yet, though, to see if something changes.
The Black Accent Package wheels appear to be leftover 50th Anniv Package wheels painted black.
California...
UPDATED WITH FIRST IMAGES OF THE 2017 MUSTANG IN LIGHTNING BLUE, PLATINUM WHITE METALLIC AND GRABBER BLUE:
Here's the 2017 Mustang GT prototype in Lightning Blue.We also caught the 2017 GT350 in the same color.
2017 Mustang EcoBoost in Grabber Blue...
If anyone has a set of Non Lighted door sills from a 50th anniversary or a 50th anniversary appearance package car that have since replaced them with the lighted sills, I am interested in purchasing your original set with the aluminum inserts. I have a base 2015 GT with the plain black sills.