Nintendo announced the bundle at E3 2014 in June, but this is the first time we're actually getting to see it. If you would rather buy the items individually, you can purchase the game for $60, the adapter for $20, and the controller for $30--thus, the bundle represents a $10 savings.
The bundle's box art also reveals the branding Nintendo will use for its amiibo toy line. Super Smash Bros. for Wii U will be the first game to support amiibo toys, though it remains to be seen how the functionality will work in the game.
Since Super Smash Bros. is one of the Wii U's biggest games of 2014, we wouldn't be surprised if Nintendo also launched a hardware bundle that includes a system and a copy of the game, but this hasn't been announced. Might be wishful thinking on my part.