I just used Uber Black in Netherlands and contrary to some of the misinformation posted here, Uber Black drivers are licensed and have insurance. It's Uber X/Uber Pop cars that you have to be concerned about. The experience that I had with Black was fantastic & I'll use it exclusively in any city that has it in the future. One of the Black drivers told me that he has a regular taxi service and he makes a lot more money driving Uber fares than his regular service. 80% of his business now comes from Uber and he is extremely happy with the money he makes from them.
To those of you who say that you would never use Uber, how many times have you used Black?