I've had plenty of poor but not shocking Uber/Lyft rides. Its nice you can rate them and get them out of the ecosystem. However, as time goes on, the bar on Uber/Lyft's drivers will lower, the cars will get dirtier and less maintained and the costs will get higher.

The stabilization point is probably close to taxi service. I think that Uber/Lyft really solve for SF's taxi problem mostly.