We've had a Flex for over 18 months now. Summary:
1) Nice outside. Many ask about how we like the car.
2) Roomy inside. Excessive for in town, but great for long trips.
3) 12" longer than our last SUV. Street parking can be more challenging.
4) Poor fuel efficiency. We get 13gph city, and about 22gph highway.
5) Build quality OK. Plastic covers on base of front seats and door handles keep popping off. Engineering falls short in the minor details.
6) Ford Service is apathetic. They do the work, but do not seem to care about customer satisfaction.
7) Navigation system is poorly designed and clumsy. Passenger can't enter address when car is moving. Media player and bluetooth works well.
Outside Appearance, Roominess, Comfortable.
Ford Service should treat Flex customers more like luxury segment.
Ford should pay attention to small details like German engineering.
Ford should advertise more accurate mpg numbers, or improve efficiency of Flex.