I played the WiiU extensively at NYCC, so I'll just post my impressions from there
Zombie U: First my experience was waiting on line and finally getting to a unit, only for me to have to wait 15 minutes while the attendant tried to get the system to work again as it froze like three dozen times and she kept resetting it only for it to keep getting stuck at the title screen. So I went to another line. This game looked like a mid-tier 360 title, with a pretty engaging atmosphere in motion.
The gunplay, though, seemed like a rather low level FPS without the strategic depth to really pull you back in, like a Halo or even a Left 4 Dead. That said, it's kind of difficult to know just how much thought you'll need to put into what you bring with you because there wasn't much time to play. I thought the screen utilization was as advertised, but the game wasn't very hard what I played and so I didn't get the fabled tension yet. I can see how it might be, though, later on, as things get crazy.
The multiplayer was actually the highlight, but it was only really special when you were the king of the zombies. Otherwise it just felt like a typical FPS multiplayer game but with mediocre FPS mechanics. Unfortunately this is worthless for me personally since there is no online version of this, and I won't be playing in-person with anyone. Most of my friends and family have moved on from gaming ages ago, or don't like to play Nintendo products.
Pikmin 3 - It was Pikmin. As I have said, you can definitely tell its Wii roots. It looks and feels like a hi res last gen game with a few next-gen graphical tricks/shaders. Like a first gen 360 game or something, so this remains supremely disappointing. The other thing is that I really REALLY miss the cool item descriptions/types of Pikmin 2, the humor isn't as obvious in this one and I can really feel it.
That aside, it plays like Pikmin and it plays extremely well. The Rock Pikmin are interesting but I'll have to wait and see how much they'll contribute to the depth of the series since they weren't utilized in any really special fashion during the demo. This remains my most anticipated Wii U game.
Wonderful 101 - This is like an old school arcade game with new school sensibilities. What a fun, slippery title that really makes use of all the positives of a Nintendo console but with none of the typical negatives. Just outrageous, non-stop fun. It seemed a little simplistic at the moment, but again it's hard to judge from the demo.
Controller - Was light and comfortable; screen blew. Will avoid use where possible.
That's all I played so far. I was on line for NSMB U but decided there was nothing I could possibly learn from the demo that I couldn't guess from looking. Didn't get to play Rayman.