Cleaner than most cabs
They come and collect you instead of waiting on a cold or wet street.
Because all of the drivers are their own business owners essentially, they are motivated to create a clean and pleasant experience. Unlike some yelpers I've only had one bad experience. One guy who went through a stop sign and then blamed me (to the cop) by saying that I was in a rush. He then was so nervous that he went through another red light. I put it down to being young and stupid. Seems to be a generational thing.
Other than that service is spectacular.
They also use gps to take the most efficient route.
Have used both uberx and uber black and both are great.