The geothermal system in question was installed in 2010. The issue is the direction the heat pump is running. In our location, groundwater is typically about 50 degrees F. So in the summer, the system is pumping "downhill", that is, warm to cold, the direction the heat naturally wants to flow. So it's efficient as h*ll - we air conditioned the entire place for $50/month in the middle of the summer, and as my wife has asthma, we ran it pretty much all season.
In the winter, it's pumping "uphill", cold to warm. A typical February electric bill was $750. Ugh.
If I someday live in someplace like Florida, where most of the HVAC is AC, I'd definitely do it again, But as a heating system the overall experience was pretty awful. I was thinking about modifying the system to heat with natural gas and retain the geothermal for cooling, but them we moved.