One-pedal driving works by effectively replicating the effects of both the accelerator and the brake within one pedal, the idea being that in situations where your speed is rising and falling frequently - such as in traffic - it makes it easier to modulate your speed and reduce battery consumption.

The retardation you feel is the braking effect, although this is partly regeneration and partly actual braking, depending on the pedal position. We would suggest it is not necessarily suited to motorway driving, where you would normally keep a relatively constant throttle.