No experience with that brand, but…. my guess is….
It will be effective if it is sized correctly to heat the space it is deployed to. Likewise a heat pump will be effective it is sized correctly for the task.
In terms of efficiency, in a well insulated and draft-proofed room, it will use about 4x the electricity of the heat pump. So not great efficiency compared to the heat pump.
If it is deployed in a room with all the doors and windows left open and the wind blowing through, then it could well be more efficient, since it heats people directly rather than heating the air. The same if you want to heat a small part of a very large space, like a desk in a warehouse or workshop, or as a patio heater outside.
In a typical poorly insulated and drafty room, the efficiency will still be not as good as the right heat pump. The heat pump will use more electricity than in an insulated room to maintain the air temperature. The radiant heater won’t be keeping the air as warm for the same level of comfort, but it will still use more electricity than the heat pump.
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