I've been a PhotoShelter contributor for several months now, slowly adding worthy images and waiting patiently. I believe it's a much better option than RF microstock in the long run.
I was also accepted by Photoshelter, but the tax rules seem quite complex for photographers based outside the US, so I'm not sure if it will prove to be the best solution for me personally.
Well, I've stuck 66 pictures online.
I wrote to them to suggest that the statistics were incorrect. Apparently they are working correctly. The one stat that really makes me suspicious is "Approximate Search Result Hits: 34862" which is obviously an extrapolation from someone's data, but not mine, that's for sure!
And strangely my microsite hits have increased exactly one per day, without fail, since I joined.
Just looking at the types of images they are promoting on their front page makes me think they are really looking for grunge / contemporary / artistic compositions rather than images that businesses might download for presentations.
It's still only two months old, so I'll give it time, but right now they haven't seen the uptake I had expected.