In a day-one patch (which took Polygon staffers about one hour and 45 minutes to download and install), much of the Wii U's online functionality was activated, including the eShop, the web browser and Miiverse.
After updating the system, users can assign a Nintendo Network ID to their individual Mii. Multiple Miis can be assigned to a console, with each Mii getting its own Nintendo Network ID. Each ID has its own friends list and purchasing data associated with it. There is, however, no "achievements" system associated with the Network ID, which means system-wide achievements are not currently supported.
Once the Nintendo Network ID is linked with their Mii, users can access the eShop.
The eShop allows users to download full retail games, like New Super Mario Bros. U and Assassin's Creed 3, as well as smaller indie games like Little Inferno and Chasing Aurora. Price points for full retail games are the same as they would be in-store, with most new games being priced at $59.99. Smaller indie games range from $9.99 to $19.99.
Having a Nintendo Network ID linked to your Mii also allows you to build your Friends List. Adding friends is much simpler than it has been on previous Nintendo systems. To send an invite, all you need is your friend's Nintendo Network ID. Once sent, your friend will receive a notification and, upon their accepting of the invite, your system will list them as a friend. Users are limited to 100 friends per Nintendo Network ID.
If you're looking to fill out your Friends List with some like-minded gamers, your next stop should be Miiverse. Miiverse is a hub for all social interactions on the Wii U. In Miiverse you can receive messages from friends and also browse a "Communities" section.
In Communities, every game is given a message board where fans can post personal thoughts and even drawings for other fans to see. You can send friend requests to strangers in the Communities section, but you can also choose to "follow them." Like Twitter, following someone doesn't require that they accept your invite. Instead, it just allows you to keep track of all their Miiverse wall posts in a tab called Activity Feed, which acts like your Facebook news feed. It doesn't seem to track in-game actions, though, so you won't be able to see which games your friends are currently playing unless you're looking at your Friends List.
The last major feature that the day-one patch activates is the built-in web browser, which seems to handle most web pages quite well. YouTube videos in particular look quite good on a TV screen or on the GamePad.
Plenty of features are still missing from the Wii U, including some media applications like Hulu and Amazon Instant Video. The Nintendo TVii app, which is supposed to allow users to view an interactive, TV Guide-style menu on the GamePad while watching TV, is also not available as of launch.
We'll continue to track the progress of the Wii U's online functionality in the coming days and weeks.