Product review (5 stars): so good. It is doing exactly what I needed for ...
Just recently had this item installed (months after purchasing it) so I could not answer until now.  So far, (knock on wood), so good.  It is doing exactly what I needed for the garage refrigerator:  keeping the freezer at 0 and refrigerator at 37 when it is below 32 outside.  Fingers crossed that it continues to perform this way!  Installer said that it is like a thermostat that will "kick on" when the temp gets really cold outside.