Miiverse has been one of Nintendo's most interesting additions in this generation of hardware, giving fans a chance to share notes, complain or post doodles to their heart's content. Though some rules and tweaks haven't always proven popular, it's still used with enthusiasm by a core of keen Wii U and 3DS gamers.
It's worth noting, if you count as one of those eager users, that Nintendo's been issuing reminders of maintenance that'll take Miiverse down for eight hours. Between 7pm Pacific / 10pm CET / 3am UK / 4am CET and 3am Pacific / 6am Eastern / 11am UK / noon CET today there'll be no service at all on any platform.
If you have a doodle to post, you'd better get a move on.