So basically, you don't know much about the Wii U but you still feel the need to put it down? Hmm...
As a Wii U owner with kids I can tell you the Wii U gamepad is a great idea. At the moment the console only supports the one Wii U gamepad, but out of the games I've tried (albeit a limited amount as there isn't really much out there right now) it works well, feels a little bit like playing on a big DS in some of the games.
It also works with existing Wii controllers (I bought a couple of compatible motion plus controllers as my original Wii controller was pre-motion plus). You can transfer saves and downloaded games, the Wii store has an app available which downloads your content to an SD card (doesn't need to be a massive one, 2GB would probably do) and then transfer them to the Wii U to play in Wii mode, although you can't keep content on the old Wii, it's moved rather than copied. I've only briefly looked at the Wii mode and it's a little clearer over HDMI from the Wii U to the TV (42" Panasonic Plasma) than the Wii to the same TV using component video (and some rather cheap phono extension cables).
I've got Nintendo Land as I bought the premium console, it's not a bad game, has a few Nintendo themed mini games in it. I wouldn't pay £45 or whatever it is for it but as a freebie with the console I couldn't complain. I also bought Mario Bros U and I'm enjoying that, and so are the kids. It can be played on the TV or on the game pad in single player mode or with other players on a Wiimote.
Other than that the new Rayman game looks interesting and makes good use of the gamepad, and Little Inferno is well worth a look (and on sale in the Nintendo shop).
As for your idea of using an Android tablet as a controller over Bluetooth? Wouldn't have worked, Bluetooth is just too slow. Wifi maybe, but then you've got the faffing around downloading an app, support costs for Nintendo if it doesn't work on a specific device and all that.
While you may not see the appeal of the Wii U (despite not having tried by the sounds of things) others do, I personally like the idea of being able to play on the Gamepad, I can either let the kids play games on it while I'm maybe watching TV or playing on one of my other consoles (PS3/XBOX360 or even my old PS2 or Wii) or I can be playing on the Wii U on the gamepad alone, or we can be watching something on LoveFilm or Netflix... whatever, it's stopped some arguements in the house and means I don't need to run a long HDMI cable from my consoles to my desktop monitor.
Oh and for me, Pikmin 3 is the killer app :-)
Maybe considering this loss and poor sales Nintendo might even drop the price a bit like they did with the 3DS.