It's a great side gig while at the same time being the world's worst full-time job...great for paying down loans, saving, and investing, but terrible as main/sole source of income. The real issue with ridesharing is that there aren't enough busy hours over the course of a week to have earnings consistently high enough to make it worth your time.
To be successful you have to be a great driver that's fully confident of your abilities in DC traffic, a friendly people person, good with the app, and drive a cheap, clean car. Good drivers who know what they're doing always consistently net $20+/hr after expenses. Average drivers make between $10-20/hr, and bottom-of-the-barrel make less than $10/hr and are likely to quit very soon after they start.
Read this too:
http://www.dcurbanmom.com/jforum/posts/list/544126.page