I have 4 heatpumps in my place a big one 8kw in the lounge and small ones in 3 bedrooms. To supplement log fires.

They don't really like very cold weather, and will go into defrost cycle if below -4 degrees C, which means they blow cold air and gurgle for 10 minutes until they start up warm again.

They do need servicing every year or so and checking on the refrigerant levels.

They are surprisingly convenient and cheap to run.

They are a bit noisy, and need be sited to blow air indirectly at beds.

They are aircon for summer too, and work well to cool the house down.

They don't work in power-cuts, so if you have winter black-outs you are out of luck

Ive only had them in for 3 years so can't comment on longevity.

I like them, but would have preferred a radiator system, but that would be $50k where I live. I looked at central air/heat, but you need more ceiling space than I have, and the cost was prohibitive. little heat pumps with simple back to back installation are not super expensive. Should have done it years ago.