Off-screen play. It's just a brilliant idea. My youngest has been working towards his golden wheels on MK8 for a few days now, and he was just so close to it when we needed the TV. So he quietly carried on off-screen until he finished it. (he uses the gamepad/pro controller combo)
Its uniqueness - very few of my kids' friends have a Wii U - but they're over at our house a lot playing it. Personally I hate the party games, but its these, and games like Tank Tank Tank that they love to play together as a group.
On a purely selfish note, for me it's the exclusives and the backwards compatibility. Nowhere else can I play MK or Smash.







