I've had more good experiences than bad with Uber. The most annoying thing is when you see several close by Ubers, and you request one but then the assigned car is much further away.
Drivers are generally less knowledgeable about the roads than red taxi drivers but the difference doesn't seem to be huge.
Out of several dozen trips I've only had two clueless drivers who couldn't work out how to pick me up. Uber automatically refunded both cancellation fees when I hit the complain button in their app.