My top 5?
1. Wifi that works.
Some people aren't having problems, but there are a significant number of people who are. I have a CS degree, and enough networking experience to go well past basic troubleshooting. Our Wii U can't hold a connection for more than 5 minutes without dropping in and out. For a console that supposedly targets a more casual market, this is doubly problematic.
4-5. See 1.
I have the same issue with the system, the Wi-Fi sucks, many times I have to go as far as deleting the connection and doing the setup all over again, it works must of the time, but come on, even tablets have better Wi-Fi connections. And why the hell can't I connect the Gamepad through Wi-Fi and play in any place with an available connection? I think those are some serious flaws that Nintendo should work on other than the dreaded battery life of the gamepad.