E3 is where Ubisoft gave people a chance to get their hands on the game for the first time. Aside from demonstrating the game's excellent pseudo cel-shaded visual style, the E3 demo was set up to give people a sense of the controls and to showcase the interaction between the prince and Elika. The controls, for instance, have been made a bit more straightforward than in previous Prince games -- it's easier to pull off moves and run on walls -- and the complexity comes from using Elika effectively.
There were several chasms in the demo that required Elika's help to safely make it across -- by hitting the "Elika button" midway through a leap, she'd give you an extra boost, effectively causing a double-jump. Elika also added support during battles, and it was possible to pull off combo attacks.