Uber was recently launched in my city after the usual municipal hurdles (Calgary). I've taken it 10-20 times and have had a different driver each time.

I always make small talk and usually ask how their experience has been. I always get a "meh" response. No driver has ever said it's awesome, and no one has said it's terrible (those drivers are likely not taking fares anymore). I can see why drivers don't remain on the platform. If you take a short break for whatever reason, you likely have very little motivation to pick up again. It doesn't seem like it's life changing for any driver in my city (one driver did say it was good for him, but he was a realtor who would hand out his business card).

I think this shows why Uber needs to subsidize so many rides when first starting out. They need to provide their drivers with tons of business, otherwise the two sided marketplace doesn't get solved.