Here's a couple of little Features that would be nice to Add ...
1 - FlashLight when Notification arrives
2 - LED when Notification arrives ( could also make the Windows Button turn on )
3 - USB HID and Eventually USB Support ( not microUSB ) , to be able to print a document or copy files from the phones to USB Flash Drive directly ...
4 - HDMI Support ???? I don't think it's supported for the moment.
5 - Show Apps by Install Date , Most Used , etc ... In fact i don't know why this wasn't on WP8.1 , there have been a lot of complaints about it , and it should be easy to implement this feature ...
But Overall , it's a pretty good Update ( Except for The Music / Games Hub )