Even though in London black cabs are significantly more expensive than uber x, they are a much better experience. I often order an Uber in the pretty busy area of Soho, only to stare at the app for 10 minutes as my driver turns into dead end streets time and time again trying to get to my location. I don't really understand why this is happening, because they usually have both a separate GPS and the uber app that should display driving directions.
Black cab drivers know so much more about the city it's not even a contest. I have almost totally switched to using Hailo in London for that reason.