When walking on it, there is a feeling of one’s body moving in an unexpected direction, but that was something he found himself getting used to.
It's been a decade since VR needed to reflect the inner ear, instead of stalking around it. For basic head-tracked uses - you know where the user's expected down-vector is, and you know where the character's down-vector is. Make them match and it'll be fine. Sit perfectly still in a virtual race car and you'll have to look up to see the horizon. It's the opposite of tilty simulators from the 1960s.