One of the advantages of living in Japan, as opposed to the United States, is you get to play New Super Mario Bros. 2 first, unless you were trying to download the full game.
Yesterday was the first day of full game downloads in Japan and it coincided with the release of New Super Mario Bros. 2. Online issues for new features are fairly routine, but it doesn't make them any less annoying. According to Nintendo, the problems have already been cleared up, but it does make you wary if you were planning on downloading New Super Mario Bros. 2 on release. You may want to spring for the retail copy, just to avoid possible disappointment.
New Super Mario Bros. 2 releases on August 19, alongside the 3DS XL.