Got a question regarding the realistic heat output from heat pumps.

Friend of mine living in South Texas has a hydronic heat pump system. Essentially a radiator run off a water heater providing the air handler the source of heat.

Overnight temps typically in the 30's. Daytime temps from the mid 50's to low 70's. Indoors the house struggles to reach 69 degrees.

I understand that heat pump systems aren't as effective as gas fired furnaces in generating heat but does this sound a bit weak?