That's it. There's no catch, it's just a promotion to get people into the eShop -- like a virtual doorbuster sale.
It's not a "trial" version of the game that ends after 30 days -- you just pay the 30 cents and you get to keep it. All Wii U Virtual Console games have full GamePad remote play support, and the ability to fully customize your controls.
With that said, Nintendo has revealed the full list of exact dates for all of the planned games, so make sure you bookmark this page as a reference!
Balloon Fight (NES): Wed, 1/23 to Thu, 2/21
F-Zero (SNES): Wed, 2/20 to Thu, 3/21
Punch-Out!! Featuring Mr. Dream (NES): Wed, 3/20 to Thu, 4/18
Kirby's Adventure (NES): Wed, 4/17 to Thu, 5/16
Super Metroid (SNES): Wed, 5/15 to Thu, 6/13
Yoshi (NES): Wed, 6/12 to Thu, 7/11
Donkey Kong (NES): Mon, 7/15 to Tue, 8/13
Virtual Console on Wii U [Nintendo]
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