I'm still of the stance that heat pumps work well, if the house heating system is designed/adjusted to accomodate.
Modern insulation, large radiators/underfloor heating? Ideal candidate, you'll hit decent efficiency most of the time.
1930s house with little insulation, and un-calculated radiators thrown in and run at 70'C?
You might as well be using bare electric heating at a lower install cost.
So the push for ASHP/GSHPs needs to be a two pronged attack: Get places ready to receive them, then install them.