The 3DS isn't an especially new piece of tehcnology, and in order to stay ahead of the curve Nintendo have taken a bold move in order to maintain pinnacle performance from Super Smash Bros. for Nintendo 3DS.
When the game is running, players will not be able to access Miiverse or use the Internet Browser if Smash Bros. is the active software. That is of course unless you're using a New 3DS.
The New 3DS with its advanced hardware will have full Miiverse functionality, just as you'd expect. It's not a large part of the game, and it's preferable to losing gameplay features, but it's a shame not to have it. It seems consistent 60 FPS 3D gameplay has its price.
All other online features such as online multiplayer are not affected by this announcement, only the aspects mentioned.
What's your view on this announcement? Let us know in the usual place.