After some initial confusion, I'm beginning to get excited. Here are 8 reasons why.
I'll be able to play HD games (and more) in my hand without having to buy a separate handheld system.
I mostly play portable games on my bed or sofa. The thought of playing a game like Assassins Creed, Batman or Zelda HD on my Wii U controller with regular buttons and sticks, is very exciting. With the Wii U, I can have a tablet device with video calls and small touch-controlled games, a HD handheld system that plays retail games and full on 'next-gen' console experience all in one. All of this for much less than those would cost separately (as long as I don't leave the house!).
I can potentially check if my friends are online, browse the web and many other things without even turning the TV on.
Miyamoto has stated that one of the ideas behind the Wii U was using the system without the TV on; it's why people didn't really get into things like the weather channel as they require turning on the TV, Wii and loading up the software. I totally agree, I never did that. Having full operability on the controller is, in essence, having a picture-in-picture feature for your TV. If Nintendo allow all major functions of the system to be made on the controller, I'll be able to buy downloadable games on the store, check what my Wii U friends are up to, browse the web and then jump into a game once the TV becomes available.

Portable and tablet-style games are no longer restricted to small screens.
The uDraw GameTablet had some great ideas, while several games have been released for it since it launched, the fact is it requires yet another accessory for your Wii. The Wii U now has a drawing tablet built in, so all of those games could easily be converted for the new console. The same goes for all the touch games of the iPad, iPhone and even the DS; some games work better with touch or stylus control and it would be great to play these with a big touch screen and a HD TV. A good example is that many people prefer the stylus controls of Trauma Center DS, but like the visuals of the Wii version - now you can have both! Of course, if the controller had a capacitive multi-touch interface, even more games would be playable.
Wii U 3rd party games will be (potentially) the best looking versions.
After years of 'Wiimakes' and downgraded ports, the Nintendo system will be the most powerful on the market, and games will be on par, if not better looking than on the other systems. Couple that with a unique and (hopefully) advantageous control system, my game library could be a lot bigger than they were for previous systems. People may argue that the PS4 and Xbox 460 will have vastly improved graphics over the Wii U in a few years time, but if you consider that they won't be out until about 2013 at the earliest, then factor in the systems will be very expensive with very few full potential games at the start, you could add another year or so onto that.
Third party games are starting in the 2nd or 3rd generation of graphical finesse.
Compare Genji to Uncharted 3 or Perfect Dark Zero to Gears of War 3; HD games have come a long way in 5 years, and the Wii U will be starting it's life at the best time, skipping ahead of the learning curve entirely. This means we don't have to play half-baked testbed games that don't push the system that much, the Wii U will be starting with some of the best looking games out there. The only unknown quantity at this point is whether Nintendo themselves can catch up quickly!

A great way to play Virtual Console games.
One of the reasons why classic 8-bit and 16-bit games look best on the Wii VC is due to its standard definition and unsmooth pixel-perfect emulation under which it presents them. With the Wii U controller's screen, we could see the same retro accuracy displayed on it, with the added benefit of having it be (semi) portable. Virtual Console Arcade games would work great too; I can't wait to play Space Invaders on my coffee table and pretend that I have a cocktail table version. Also, all those fan-made portable Super NES, N64 and GameCube machines are now an official accessory by the very function of the Wii U! I just hope the way of browsing and selecting games is done in a more intuitive way. (iPad style bookshelf option please!)

I won't have to buy batteries anymore.
A controller with a dock - finally! I also hope they make third iterations of the Wii Remote and Classic Controller with rechargeable batteries included too.
I can play Pacman Versus without any additional accessories.
That's it. I can potentially play a HD Pacman Versus without a single wire in sight.
Are you excited about the potential of Wii U? Sound off below!