It isn't really fast in any of it's moving modes, or actually "rolling like a wheel" as it claims. It also looks a bit ridiculous creeping along on the beach in caterpillar-mode. And on top of all that it seems to create an awfully loud screeching noise.
But what counts is the diversity of possiblities achieved by the modular design at work in Superbot developed at University of Southern California.
Superbot consists of module-blocks which can arrange themselves into a number of different shapes, among them a humanoid and the above-mentioned caterpillar.
"Each "Superbot" module is effectively a robot in its own right. The modules can move independently, flip over and rotate like wheels, and have 3D accelerometers that let them know their precise orientation."
Videos: rolling like a wheel, inching along like a caterpillar, climbing slopes, climbing ropes and finally walking like a humanoid.