The eShop maintenance is over, and now the games begin.
http://www.nintendoworldreport.com/news/48395/nintendo-switch-online-live-for-all
Tonight's eShop maintenance is officially over, and Nintendo Switch Online is officially live.
The free trial can be claimed on the console, which automatically starts a 1 month membership that can be immediately cancelled. The special NES Joy-Cons can now be ordered on the Special Offers page.
NES Online is now available as a free download in the eShop, with online play supported. Users with foreign accounts - notably, Japan - can also download those versions of the application and play the games with Famicom box art.