Yes, I'm not normally prone to motion sickness, but the change of perspective during a turn is quite unpleasant.

Yeah it made me feel the instant onset of what I recognize from vast personal experience as motion sickness. I would never be able to use this.

Even aside from that, the constant feeling of going downhill would be off-putting to me.

It's already been done - VR

Nausea as a service, while begging for investments...