Even though I didn't get to experience the new controls, I did see new graphics and the new Rock Pikmin. The Wii U's HD output amplifies all the Pikmin-ness of the series: the forest looks more lush and beautiful (and still preternaturally clean), the Pikmin look even tinier and more ant-like, and there's a nice subtle tilt-shift effect to drive home the "tiny" look.
This ant comparison is further assisted by new actions; I watched red Pikmin (one of only two varieties in the demo) pick up chunks of rock to build a bridge over a small creek, so I could more quickly return home with the fruit they'd picked up. They grabbed stones, walked them over, and placed them single file. Later, they spotted a pile of gold nuggets, then of their own volition grabbed them and slid down a curly vine to deposit them.
The new Rock Pikmin are used as a blunt instrument. You direct them to fly directly into whatever you want broken, and they do so with their body weight. This action breaks glass barriers, floating jellyfish monsters, and, most spectacularly, the segmented armor plating of a gigantic caterpillar boss, allowing the red Pikmin to grab onto the exposed weak spot and do damage. The boss, of course, didn't just stand around and allow this to happen: it scurried across the screen, occasionally hiding on a side wall, and then dashing out to grab some of my poor critters in its pincers.
It's difficult to evaluate the promise of Pikmin 3 without exposure to its greatest interface-based innovations, but even looking at it from the myopic view of the E3 demo reveals a lot to look forward to -- it's Pikmin, but prettier, and with more ways to interact with the environment.