The only issues still on mind
1)
Nintendo using System Codes on the Wii to tie all your Nintendo Channel stuff, Friend Codes, etc... and then when my machine needed some Nintendo warranty covered repair, they sent back a refurbished Wii with a different System Code (resetting me, making some save files on SD card unuseable, etc)
Plenty of System architecture stupidity on the Wii. I really hated Nintendo for many of the bad bad decisions they made on Wii to just smash on the potential of the things they did get right (motion controls are fun when done right, the form factor of Wii Remotes with Nunchuk is great, virtual console, etc).
Glad they realized their flaws and clean break fixed those issues on Wii U. Nintendo Network redeems them on many things and they add some really nice meaningful new services like MiiVerse.
2)
Wii didn't release with WiiMotion+, although that technology just wasn't ready at the time... but still. I was fine buying the new controllers with Motion+ built in, but too few games on Wii assumed people would have the right controller and therefore majority of new releases didn't take advantage of it.
For Wii U, I am glad that WiiMotion+ controllers can be used and are working well, but I also wish that Nintendo had upgraded them for Wii U by using the 9-axis motion controls tech they have put in the Gamepad. Supposedly it's a size of technology issue preventing it being put in the WiiMotion+ controllers to further improve them.
3)
The various Nintendo eShops not sharing the same Wallet is a problem. Wii has its points still stored there, the 3DS shop has its own wallet with amount stored, and now the Wii U has its own wallet with amount stored.
4)
Voice chat should just work directly off the Gamepad... it has very competant speakers and also a Mic built in which work perfectly for the Wii U Chat thing, but not for voice chat within games that support it? Why should I get a headset? Also, why doesn't the Pro controller have speaker built-in or headset jack... heck why doesn't the system have wireless headset that doesn't need to be plugged into any controller (i.e. more like PS3 and less like X360).
