Basically yes.
It adds some efficiency because once you have a radiator full of hot oil in the radiator it tends to release the heat for a long while after the electric is shut-off.
Most electric space heaters send a plume of hot air arcing upwards.
You end up with a nice heat storage device to radiate warmth at the level you want to use it for longer than a normal resistive space heater using the same energy.
It has its uses.
Like most bespoke items they’re good at some things, not everything.
It’s nice if you’re trying to keep an indoor living space warm for a longer period, like overnight.
They typically have a thermostat setting on it to maintain the temperature.
It doesn’t make the same noise as a blowing space heater, as there’s usually not a fan. I’ve heard creaks and such from them.
As noted, the radiative effect can last for a few hours depending on energy loss in the space.