New condo forced air heating -- expensive to run?

I've been looking at some new developments, and it seems that the days of the good old baseboard radiators or steam radiators are gone. Everyone's got hyronic forced air or ductless mini-split systems installed. So the question is, has anyone bought into a new building with these types of systems, and how much are your operating costs to heat in winter, and cool in summer? Astronomical? Reasonable? Cheap? Also heard that the mini-split systems basically stop heating when the outside temperature drops below freezing and need a backup heating source. Would love to hear some thoughts from those with experience with these units. Thanks!