As a first timer, I downloaded both versions. Tried only the bunny.
For the 3DS, I don't understand the touch D-Pad. By the time I got the bunny in my sights, it slid out of the way, meaning I'd have to get the camera right then attempt to attack. Constantly kept mowing me down because of it. That wasn't fun at all.
For Wii U, it looks pretty. Only tried it for a few minutes, realizing it would take a while. Give it a better shot when I got a chunk of time. I think that'll be my best bet if I like it and want to buy since that touch D-Pad on the 3DS version is terrible and would drive me crazy.
Overall, I'm totally lost in terms of what I'm doing, the controls, inventory items, the two little dudes following me around. Wish it had some walkthrough in the beginning. I'll keep playing around with the demo but it seems like a tough game to grasp for a new player.