I know a gentleman who swears by oDesk, mostly as a billing/mediation platform for custom Twilio apps. I wouldn't touch it with a ten foot pole, but he charges enough to make it viable.
I was at the Twilio conference this year and there was a talk from Tim Lytle who only uses oDesk for his clients. He claims to have a pretty good client base and is busy from the work.
Twilio also endorses oDesk as a platform for people to find qualified programmers http://www.twilio.com/blog/2011/06/twilio-partners-with-odes..., maybe the answer is to specialize and differentiate to become more successful when competing against $10 per hour international outsourcers.
Short version: it adds nothing I need, positioning myself against the competition there would be certifiably insane, and the type of clients I most successfully work with would avoid me like the plague if I proposed working through oDesk.
