Though the Wii U had decent initial sales from its launch through the end of 2012, numbers from Famitsu indicate that the new console is experiencing a sale slump. Recent figures show that the Wii U went from selling 70,000 units in a week to 21,000 the next in Japan, matching the PlayStation 3's sales.
Though there's certainly cause for concern, Nintendo's not under too much hot water just yet. Though Sony and Microsoft are expected to unveil their next-gen consoles in the coming months, it'll still be time yet before they hit store shelves. Not to mention, Nintendo's bread and butter has almost always been its first party titles, which most have yet to hit the console. There's no doubt that sales figures will rapidly pick up once Pikmin 3 or the new Super Smash Bros. rolls around.
Nintendo's 3DS wasn't performing to expectations when it first launched, but with a price drop and good releases, the handheld's sales have picked up extraordinarily. Hopefully for Nintendo, the Wii U will be able to make the same kind of bounce back.