I've noticed an almost total drop off of sales via promoted listings (where you pay a % when the item sells).
My stats:
February - April 39 items sold
May till now 2 items sold
It is pretty well the same base of stuff I have listed, as far as I know.
I really haven't had time to try to figure out why.
Searches that used to return my stuff still return my stuff predominantly so it doesn't look like my stuff is getting less exposure.
It is possible that promoted items will only work on so many people for so long, and any that would have seen my stuff have seen my stuff.
Might also be the reason for the "new" and "improved" click based advertising thing (aka highline search ads) they're introducing....they don't get paid if nothing is purchased, the new click things they do get paid even if nothing is purchased.....
Would be interested to know if others have seen a change in promoted listings results over the course of this year....