Product review (5 stars): Great Buy, Great Unit
What's not to love?  Looks beautiful, works great, well designed.  Great features.  Lots of built-in options for various foods, both cooking and defrosting.  We also like the two position under-the-unit light, the two speed fan and the on/off feature for the turn table.  And the unit is very easy to clean, inside and out.

I've read other reviews on similar GE over the range microwaves, with complaints that, "The fan came on unexpectedly and would not shut off and that the inside of the door 'steamed up.'"

The instructions state that if the unit gets over heated from the stove below, the exhaust fan comes on automatically to dissipate the heat, so as not to damage the microwave.  When it cools down, the fan automatically shuts off.  Also, when you heat items that contain water, it will naturally emit steam.  In fact food must contain water for a microwave to work.  Microwave ovens work not be heating the actual food, but by heating the internal water in the food!

Our previous counter top microwave was 10 years old and still worked fine.  We just wanted more counter top space and a larger unit.