I am planning to build a retirement home this fall and I am looking at geothermal systems.  Has anyone out there in New England had a geothermal system for a year or more that can tell me about their difficulties and successes with these systems and any issues I should focus on.  I am not mechanical and its just me so I don't want a high maintenance system but do want fuel efficieny.

Im only as far north as ct but the reason you have heard dont do heat pumps is because the lose the effectiveness around 35 degree's . Basicly its to cold for them to absorb heat from the outside. This is not the case with geothermal because we extract heat from the ground not the outside air ( The temp in the ground stays pretty constant). The reality is the longer your heating season the shorter you return on investment period is . And with commericial states usualy have allot more incentive programs available then just for resisdential. So Yes they are worth it in your area . I have installed 2 that have ben though 1 winter and just finished a complete retrofit at my parents , no issues yet

Bristol,
Half of us here are in the business of selling heat pumps so we may not be who you hoped to hear from. As you shop, ask for plenty of references and follow-up.
If you've done your home-work you already know that geo systems are 4 times as efficient as gas appliances so even if reliability wasn't as high as it is (more reliable than a gas furnace), you'd have plenty of savings to pay for repairs.
If you want fuel efficiency, you can't beat geo.
Good Luck,
Joe