I started freelancing not so long time ago, but I was at the end of an odesk. I started to work on both platforms (elance and odesk) at the same time and I must say that on elance was easier to get a jobs, but in odesk was more better quality jobs, rates was higher, customers seemed higher profile.
Then odesk changed name to upwork, here dramatically increased number of low paying jobs. Seems like bad quality jobs here are more than good ones.
If management will start implementing also some procedures for client screening, ban low paying ones, make warnings about late payments, etc. then this can be cleaned up pretty fast, but upwork doesn't want do it, because they are short sighted and clients pays commissions (ok, not directly, but You get a point).
For now I got great clients, but will in the future I will be looking for new ones here? Not so sure about it, unless something will not change dramatically.
Jon, I registered for oDesk and Elance at the same time. I found very little success on Elance and also found better-paying clients on oDesk.
**edited for Community Guidelines**