Well it's out in North America today. Anyone got one?
From what I heard from people who bought one:
The GamePad is really light and very comfortable and easy to carry.
EShop has a very strong selection of retail games.
Internet browser runs smooth and is better than the Wii's browser.
GamePad is required for the full experience.
Portability with GamePad is good, but has some problems with disconnecting but reconnects easily.
Can easily connect to 3DS and transfer your Miis to Wii U.
Has a good selection of launch day titles.
Though they say it has problems such as the the initial setup and configuration takes a really long time.
MiiVerse has constant system errors.
Tons of updates.
Though the system is still new so some of the problems will likely be fixed from time to time.
I'm still pretty impressed with it though so I'm getting one to see for myself. I like the fact you can keep playing even when the TV is not on. That's basically the one thing that convinced me to get one.