From Union Station in DC I take Uber, even though the cab line is way more convenient. It's about 40% cheaper accounting for no tip. Silicom Valley subsidizes my morning commute!
What I have had, not commonly but often enough that it no longer surprises me, is extremely racists statements about where I live (I'm a white south sider which seems to attract crazy talk). This has occurred in taxis, Uber & Lyft. I've even had Uber and taxi drivers (Lyft isn't immune, just small sample size) try to refuse to drive me home after picking me up. I've reported these incidents to either 311 or the respective apps. With the apps I have no idea of the effectiveness. With 311 I had a case number assigned and received an update months later when a driver lost their license over a racist incident.
If I really had any complaint about Uber & Lyft is that it seems to have driven the profit out of livery cars and really created a race to the bottom in that market. I used to much prefer private cars for most things, but now the difference isn't worth paying for except for prescheduled events.
All that said, I use taxis, Uber, Lyft & livery cars with some regularity, and my usage of them largely is based on convenience not quality of service. Taxis when I'm in the loop or some other busy spot, Uber/Lyft when I need an adhoc ride elsewhere, and private cars for scheduled rides.
I do regularly get cabs who say their card reader is down, at which point I just say "you are required to accept credit cards", and they always back down. I agree though that this is a reason to use Uber.
To balance the anecdotes: I once took a yellow cab to an NYC airport, and in the middle of the highway (didn't even pull off to a shoulder) the cab driver stopped his car because his English wasn't good enough to read the signs. He just kept asking me "left? right?" as cars blew past him at 45+ mph, honking their horns.
I wish yellow cabs had a rating system so I could've given that driver 1-star like I did the Uber driver.
I use Uber for one simple reason: It's 30% cheaper than a cab. It isn't the quality of the cars, the personality of the drivers or the nature of the service. All of those things vary from case to case for every transportation service. Uber's only compelling feature is their lower price.
From what I understand, the average Uber driver makes very little money, < $9/hr after Uber's fees and vehicle maintenance costs. And the low customer prices are effectively being subsidized by venture capital money. How long can this last? Could this be another Groupon situation, where the Ponzi scheme doesn't fall apart until after Uber's IPO?