Players will now directly control the creature in "a series of quests and adventures in a kind of open world that you can take at your own pace." New parts can be added that will translate to new motion-controlled moves. Some moves, like jumping, will open up new areas to explore. EA is currently "taking a look" at MotionPlus for Spore Hero, for improved sensitivity for the motion-based gameplay.
This sounds a lot like the DS's Spore Creatures -- whose sequel, Spore Hero Arena, is still scheduled for a fall release on DS.