Robots walking is definitely one of the harder things to accomplish in humanoid robotics. The human walk is a constant controlled fall broken by a series of sudden stops and rebalances: we fall forward, then move our leg to offset that fall by moving the body forward, upward, and away from the leg we just used; then, we fall again until the leg does the same.
So walking is a pain: you have to risk the chance a leg doesn't work. Then, there's shifts in ground, sidereal vectors, and a ton of other factors (speeding up and slowing down). We humans do this, albeit imperfectly, using experience and a rapid control over our own systems unsurpassed.
Robots have to be programmed to do these same things. So, to have a walking robot which can compensate for this is pretty amazing -- and they're just getting started. Running, walking with loads, and other bipedal motion tasks are on the list as well.