vWii is completely fine, nothing changed on it ;D
The major changes are in Wii U mode, all I noticed was:
*Apps/Wii u menu load MUCH quicker!
*the screen size adjust is in settings now instead of only miiverse/shop
*You can go straight to wiimode by holding B while the screen says 'Wii U' (The screen you get when turning it on)
Oh yea I forgot!
*Some icons changed e.g. the button which switches from gamepad to wiimote
*Miiverse is better (Slightly more features)