run! teleport! ignore! puzzle! go go go!
Since most people think walking speed is too slow, but Tainted-Trixter and me think walking speed is OK, I say to put in a "run" button.
I agree with suggestions for making teleportation quicker. Have the robot turn into a red streak off toward the ball with a super-fast screen scroll towards it.
Ignore suggestions to make the robot jump farther. Tell those reviewers that they just need to suck less. :D
And as coaster1235 pointed out, it'd be nice to have increasing dependence on puzzle solving rather than pure platforming as the game progresses. Maybe multiple different teleportation spheres to manage, wormholes (maybe some that will teleport just the robot or just the sphere), "enemies" that will interact with the sphere (carry it around) in often bad but sometimes beneficial ways. Making doorways that go from one screen to another and whose paths can be altered by flipping switches and requiring teleportation balls to be left in strategic areas to navigate back is one sure way to drive gamers batty.