@BenR , you missed one...!
@BenR Rating of the car, driver and *route taken* after the trip.
I have had more than one refund when the GPS sent the driver on an incorrect route (not sure how!).
Oh and for all those complaining of the surge pricing, it is avoidable if you walk a 100m (or so). The surge is set by Uber in response to a large number of hailers in a given area. The drivers can see each other and *choose* to go to that area. If you walk away from the area, the surge no longer applies.
Thank you Mike (Uber Driver) in Miami for explaining that...;-)
P.