We had one installed in our underground home and it lasted twenty years. We loved it and put in the second unit when we could no longer get parts for the 1st unit.
We lived there more cheaply than one could believe and saved a ton of money in living expense. We have sinced moved, closer to town, and are now on propane. We are considering switching to a ground source system, but will probably need two units for the size of the house we have now. Our friends have two units for their house and have been very happy with it. It was one of the most even and cleanest heats I have ever seen. I miss it terribly so now, so would be within the next couple of years we have ground source again.
I don't think you will be sorry with it, just get a reputable dealer and be sure your unit is big enough or even a little bigger than you need. Get quotes and talk with several dealers to get a feel for whether they know what they are doing or are just playing at it. Good luck and let us know how you like it after you have had it for a whlle