I haven't joined because I had no idea what it was, to be real I think I´ve heard about it before the HF, but I din´t had much time to look into it. Which I´m doing right now, and the concept looks interesting, I'm probably joining soon.
I think this concept is very similar to what @smartsteem offers, which I use almost since I´ve created an account (avoiding wasting Voting Power). It is always good to see some competition, maybe they will pay more!