Ok, I've been trying not to respond to the controller talk, but I just have to nip this in the bud.
Well, I'm talking about clickable sticks, analog sticks, and a really, really stupid button cluster/d-pad location.
You may not like the button placement, but stupid is one thing it's definitely not.
I haven't used the Wii U pad, so I can't speak for how it feels in the hands, but I think I have a fair idea
why the pad is the way it is, and in particular why they changed it from the earlier design.
First things first, the controller is built around the touchscreen. This may seem obvious, but you have to keep in mind that use of the touchscreen is paramount in every decision Nintendo make with the controller. If Nintendo goes with the traditional stick/button arrangement (with the secondary sticks/buttons at a ~45º angle down and in from the main sticks/buttons) that pushes the the default thumb position away from the touchscreen, and hence makes it more awkward to get to the touchscreen quickly. Nintendo want to make it as quick and easy as possible to move your thumb across to the touchscreen, so the slide pads are right next to the screen.
In order to do this, of course, they've had to move the d-pad and buttons directly below the slide pads. Here's the important thing, though, unlike on traditional controllers,
you don't twist your thumbs down to the d-pad/buttons, you slide your hands down. This is why they got rid of the contours on the back of the pad, they would have made it awkward to slide down that little bit. It's also why the controller is so tall, to make sure there's enough grip when your hands are in the lower positions. In addition, while your hand is in this lower position, you still have the touchscreen in easy reach.
On the choice of slide pads, the reasoning is likely exactly the same, the slide pads are flatter than analog sticks, so make it easier to reach across to the touchscreen. Personally I have absolutely no problem with slide pads, after having used the 3DS one quite a bit. The only two complaints that could be leveled at that (not enough travel and insufficient grip) both seem to have been addressed on the Wii U pad. Clickable sticks are something I'm glad to be rid of, they're an incredibly awkward input method, and anyone who can't design a decent FPS control scheme with two slide pads, 12 buttons and a touch screen doesn't deserve to call themselves a designer.
The one feature I will say they're in need of adding is analog triggers, which hopefully we'll see in the E3 version.