Like any VR without a treadmill, they won't require you to run in place, nor will you ever bump into walls.
But if you are interested, they do have round treadmills and those work pretty well. e.g the Omni treadmill:
http://www.virtuix.com/It'll be interesting when
some company actually releases a piece of hardware, rather than all these dev kits we've seen for the past 3 years.