I'm an Uber loyalist!! I've used Uber in Phoenix a handful of times and in San Francisco and San Diego as well. My Phx Uber drivers have all been absolutely stellar. They know where they are going, their price comes in at or under the estimate, they're friendly, the vehicles are spotless, and they even offer bottled water.
But here is why they get five stars: I recently reviewed an Uber ride in SF 3/5 stars. Not a horrible ride, but not great. The driver didn't really know the best way to get to the destination as one could plainly tell by the map of the route actually driven. In my book this is normal for a taxi, but NOT for Uber. I received an email the next day acknowledging the issue, telling me how they would attempt to prevent this problem in the future, AND gave me a $5 credit towards my next Uber ride. Uber provides a service and has top notch customer service to back it up. I wish all companies would do this!
Lastly, the improvements they've been adding have all been welcome additions, such as the ability to split fares between people and the addition of UberX vehicles. I have not experienced any problems with the app on my iphone, which is icing on the cake.
Do yourself a favor and start using Uber to get around town. With UberX, the prices will be even cheaper!