This is a very nice luxury SUV. The interior is well constructed and seems quite solid. The leather seats that come standard on this model are extremely nice and well made. The stereo system sounds very good. The gauges and controls / cupholders, etc. are well thought out.
The exterior of the vehicle seems very solid as well. I worried a bit at first because there is a lot of plastic body cladding on the car, but I have had no problems with any of it falling off and it seems well connected.
The engine and drivetrain are silky smooth and seem well mated for most tasks. I have noticed that the motor in this vehicle has somewhat less torque than the Jeep Cherokee that we used to own. Usually this is noticable only when towing something heavy at high speeds, like a boat. Is it a problem? No, not really. With the overdrive off it is hardly noticeable. I have noticed that the gas mileage IS pretty horrible. I think that I am currently getting around 15 MPG in town, 18 on the highway. This can be painful with the price of gas around $2 a gallon...
Despite the poor gas mileage, I highly recommend the purchase of a QX4. It is a fast, good looking, reliable, comfortable vehicle.