Not sure if anyone's mentioned this, but I feel like it may be worth knowing if you're trying to pick a version or if you plan to purchase a lot of digital content.
Taken from NintendoLife
(you can find it stated in various ways on several sites if you Google "Nintendo Premium"):
During today's Japanese Nintendo Direct presentation Nintendo introduced a new dimension to their online offering, called Nintendo Network Premium. It's a loyalty program similar to "PlayStation Plus" offered on PSN.
It is believed that this is only available with the Premium Wii U package ...
The Nintendo Network Premium service is designed for users who intend to download lots of content and includes a 10% discount on games in the online store.
Other sources are claiming that the 10% discount is given in a digital currency which can be turned into points that can then be used to purchase other games/DLC.