I use Uber a lot especially in NYC. Cars are much nicer. Much more reliable. Easy to get even in peak periods. From the airport can be cheaper than cabs when you factor in tips and especially if you use Uber X.

All of this is less of an issue in Tokyo. I do think there is room in the market in Tokyo for longer distance trips (i.e. to/from the airports) with lower fares. The drivers who contract with Uber will tell you the big advantage of Uber is the fact that even though they make less money per ride, they always stay busy while they're working. In Tokyo, if a driver could do 4 or 5 RT to NRT from Tokyo with fares in both directions, they could easily charge 1/3 of the normal rate and still come out way ahead. The problem with taxis in Tokyo is they're driving empty 75% of the time.