I've had a GeneralAire for about 15 years. I had it installed on my old furnace, which has since been replaced. I just had the HVAC guys install it on the new furnace and it's still going strong. It keeps the house humidity in the 40-50% range which keeps things comfortable (no dryness or static shocks).
My humidistat is mounted on the return air duct and I keep it set at 45 degrees (supposed to set to outdoor temp) most of the time. If it gets really cold outside I'll get some condensation on windows. If it's going to be a prolonged cold spell I'll turn the humidistat down.
Not much maintenance. I just change the pad yearly (cheaper if you buy online), make sure there's water flow, and the damper is wide open before each winter.
This is the updated model of the one I own:
http://www.generalfilters.com/produc...fier_PT12.html