I experienced the same thing about a month back, when I initially gave the trial a play (nice game, and the trial zones were comparatively well populated), then picked up a cheap box copy and moved from a lively game to a ghost-town. The first non-starter zone I visited had, for a good part of the time I was there, no other players in that zone.
I cancelled my sub after only a week and left feedback that the game, as it stood, wasn't worth a subscription with its current population levels.