The DLC is only part of the "Coin Rush" mode, an interesting way to circumvent the trickiness of adding new levels/worlds to the existing single player map.
I say interesting, more like unoriginal/lazy.
It's the digital equivalent of the eCard levels, great, but I don't want to have my new (note: PAID FOR) levels presented to me in an awkward fashion or as a bonus event.
Am I being harsh here?
Why not just have an endless "bonus world" where you can practice the stages before undertaking the Coin Rush challenges. Also are these StreetPass only? Great for me and the Famicast crew, but what about everyone else?
I hope they have the ability to share to your friends over SpotPass...
On a positive note, bravo to Nintendo for emphasising the fact that these are in addition to main content and haven't even been made yet. (although I did spot a slight nervous twitch in Reggie's eye as he said it!)
Here's hoping they go CRAZY experimental with these bonus stages as they don't need to be part of a world theme.