having had a few Expeditions as rentals (Arizona and Seattle), i think they are the best large beastly SUV you can get. they handle well on the highway, have good power, and are relatively comfortable. they are also bigger than the Durango on the inside, but harder to maneuver in parking lots. visibility it just OK.
look out for beat up interiors. as with most Fords, the interior materials are inferior and break with the slightest bit of pressure. watch out for folding seat handle mechanisms and door mechanisms in particular. BOTH our rentals has issues with this.
also check for poor AC service. Both rentals i've driven had mediocre to poor AC (especially in the back) on days hotter than 80. not sure if it's a service or design issue.
we averaged 13.4 MPG in Arizona with 7 adults and luggage in 90-100 degree heat.
we averaged 13.8 MPG in Seattle with 7 adults and luggage in 80-95 degree heat. (before the window was smashed in at the hotel parking lot and we switched to the Durango which got 14.1 MPG)
if it's what you want, go for it. there's not much better on the market in that price range.