You know I believe a 2D Sonic game is perfect for the Revolution controller. The simplicity of it would be awe-inspiring.
The game would only need 2 buttons, and be designed to take speed to a brand new level.
Here is what I mean. Use the Controller as a simple analog stick. Point right to move right and point left to move left. The more you point in that direction the faster you go. The amount of Speed Sonic maintains is completely up to you...however the faster you go you begin to lose some control of Sonic (It takes longer to move the controller into a resting or breaking speed.) As you memorize the levels and hone your reflexes you can run Sonic faster and faster through the levels.
A would of course Jump, and The Faster you go the higher and further you jump. B would roll you into a ball. Or in the air you can hold it and Dash attack even faster. (Down, Up, Left, and Right) These can be used to help dodge enemies and move about the level better.
And its that simple. for controlling Sonic.
Level design should incorporate tons of interactivity with the environment...all designed to make Sonic feel like he can't stop moving.
Railsliding, Swinging from vines and other objects, Wall Jumps and much more should be incorporated in the dense levels which are designed to allow Sonic to traverse horizontal and vertical through the levels.
The game should just be Sonic and drop the other characters...lets go back to his roots. Keep Robotnik, but call him Doctor Robotnik. Keep Robot Sonic from the Sonic CD game, and create giant Robot Monsters for bosses instead of Robotnik each level.