It may be anecdotal evidence to most people, but anyone who follows gaming is aware of the fact that were it not for Wii Sports the original Wii would not have been the sales giant that it was in the last/current/now dying generational console war.
The Wii-U really isn't offering you anything that either the original Wii or the newer consoles already do. Want child/family friendly games? Keep your Wii or get an ipad. Want hardcore games with online matchmaking and a network to keep track of friends? You have that with the PS3 and Xbox 360.
I'm glad the numbers are starting to show what I was saying two years ago. The Wii-U will flop and Nintendo will either go the route of Sega and simply develop games or they will stick to the handheld market....which is dwindling now that you have tablets or smartphones in nearly everyone's home.
For me, Nintendo died after the SNES. I haven't enjoyed any system they've made that has come out after that.