Mostly the normal stuff you'd check on a vehicle that is getting older (14 years old now) and over the 100k mile mark. Check for rust in the usual places (lower door edges and liftgate bottom edge), take a look at the power steering lines that go over the top of the driver side strut tower and the transmission lines that go along the passenger side for any signs of heavy corrosion. Find out any maintenance history you can.
If it has 4WD make sure it switches between modes OK. Check that the rear climate controls work as I believe some people have had the coolant lines (for the heat) going back there go bad, and some just cap the lines off and not use the rear controls.