Like charactor control with toggle pads and a user can walk over a fixed sized game or terrain. I'm not sur if this has been posted alredy if it was I'm sorry, but if anyone ca link me to a tutorial.
Penelope, a tutorial provided by Unity, has components that will show you how to setup touch controls on a game: http://unity3d.com/support/resources/tutorials/penelope.html
Touch controls are complicated, you need to be at least an intermediate scripter. However, Unity 3 does ship with some preset control scheme prefabs that you won't have to do much with besides drop in the scene.
For a 2D Platformer, you should go through 2D Gameplay tutorial: http://unity3d.com/support/resources/tutorials/2d-gameplay-tutorial
Don't worry about 2D art until you have mastered 3D stuff. When you are ready, say hello to Sprite Manager (free) and if you have the money, Sprite Manager 2($200).
http://www.unifycommunity.com/wiki/index.php?title=SpriteManager
there is a iphone/android 2D Game prefab on gameprefabs.com, also a great starter kit on the asset store…if you really want to go easy:)